Electroplating Apparatus

ABSTRACT

An apparatus and method for simultaneously electroplating at least two parts in a series electrical configuration in an electroplating system using a shared electrolyte with excellent consistency in thickness profiles, coating weights and coating microstructure. Parts in high volume and at low capital and operating cost are produced as coatings or in free-standing form.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional application based on Ser. No.12/081,623, filed on Apr. 18, 2008, the entirety of which isincorporated herein by reference.

FIELD OF THE INVENTION

The invention is directed to simultaneously electroplating metallicmaterial layers onto multiple parts in an electroplating system having acommon circulating electrolyte using DC or pulse electrodeposition. Twoor more parts are electrically connected in series to form a string andone or more strings of parts is/are simultaneously plated to producearticles with consistent layer thickness profiles and consistent layerweights.

BACKGROUND

Modern lightweight and durable articles require a variety of physicalproperties which frequently cannot be achieved with conventionalcoarse-grained metallic materials. Synthesis of fine-grained metallicmaterials using electrodeposition is described in the prior art. Forstructural applications these electroplated or electroformed partsrequire much greater thicknesses than used in coatings for wear,corrosion or aesthetic purposes, i.e., the required thickness ofstructural metallic layers range from 25 microns to 5 cm and, unlikeprior art applications, the structural layers and coatings requireweight and thickness tolerances not consistently achievable withconventional rack plating techniques where all parts to be plated areelectrically connected in parallel. Unlike thin coatings, in theseapplications the weight of the electroplated material typically rangesfrom 5-100% of the total weight of the article.

As conventional rack and barrel plating, constituting “parallel plating”characterized by poor individual part thickness and weight control, doesnot provide sufficient part reproducibility and industrial settings donot permit plating one part at a time in a plating cell to achieve tightpart weight and thickness specifications, plating methods are soughtenabling the economic and simultaneous production of parts by a processwhich is readily scalable.

Methods for producing multiple parts in a single plating tank using DCare known.

Andricacos in U.S. Pat. No. 5,312,532 (1994) discloses amulti-compartment electroplating system for electroplating two or moredisks simultaneously such that the electrodeposited material issubstantially uniform in thickness and composition. Electroplatingsolution is circulated between a reservoir and a multi-compartment tankwhich has one cathode-paddle-anode (CPA) assembly for each compartment.Each CPA assembly has an anode, a cathode adapted for holding a waferand employing a single thieving electrode which covers the entire floorof the compartment not covered by the wafer, and a paddle. Andricacos'plating process specifies the use of one power supply to provide currentto every anode-cathode set and a second power supply to provide power toeach anode and thieving electrode set.

SUMMARY

It is the principal object of the invention to simultaneously plate atleast two parts, in a series electrical configuration in anelectroplating system using a shared electrolyte, with excellentconsistency in the thickness profiles, the coating weight and coatingmicrostructure in high volume and at low capital and operating cost.

It is the principal object of an embodiment of the invention to providea method for simultaneously electrodepositing a metallic layer on eachof at least two permanent or temporary substrates comprising the stepsof:

(a) electrically connecting a plurality of ionically intercommunicatingelectrodepositing zones in series;

(b) supplying electrical power in series from a single source to atleast two of the ionically intercommunicating electrodepositing zones;

(c) immersing each substrate of the at least two substrates in aqueouselectrolyte shared among the ionically intercommunicatingelectrodepositing zones;

(d) supplying a negative charge to each substrate and providing equalcurrent flow to each substrate.

It is an object of each case of the first embodiment to provide a methodfor simultaneously preparing a plurality of plated parts with eachcontaining an electrodeposited metallic layer on at least a portionthereof, where each electrodepositing zone has at least one cathodicregion and the substrate therein is rendered cathodic in order toelectrodeposit a metallic material on each substrate in eachelectrodepositing zone.

It is an object of a preferred embodiment of the invention to provide amethod where at least four articles are electrodeposited in two seriesstrings simultaneously with each string powered by a different powersource and wherein said power sources are synchronized to minimizevoltage fluctuations from electrodepositing zone to electrodepositingzone.

It is an object of the invention to provide a method where theelectrodepositing parameters are selected so that the electrodepositedmetallic material layers have a same microstructure selected from thegroup consisting of an average grain size ranging from 2 nm to 5,000 nm,a coarse-grained microstructure with an average grain size over 5,000 nmand an amorphous microstructure.

It is an object of one case of the invention to provide a method wherethe electrodepositing parameters are selected so that all theelectrodeposited metallic layers have a same graded grain size.

It is an object of an embodiment of the invention to produce multipleparts simultaneously in a plating system using a shared electrolytecomprising electrodepositing metallic-materials optionally containingparticulates as a coating (on at least part of a surface of a substrate)or in free-standing form. The electrodeposited material representsbetween 5 and 100% of the weight of the article. The microstructure ofthe metallic material preferably has a crystalline microstructure with afine grain size, i.e., with an average grain size between 2 nm and 5,000nm. The microstructure can, however, also be amorphous and/orcoarse-grained (average grain size >5 μm or >10 μm).

The temporary or permanent substrates to be provided with a metallicmaterial layer electrodeposited over at least over part of a surfaceinclude flat plates, tubular objects and/or complex articles. Articlesmade in large volume using the process described include medicalequipment including orthopedic prosthesis, stents and surgical tools;cylindrical objects including gun barrels, shafts, tubes, pipes androds; molds and molding tools and equipment; sporting goods includinggolf shafts, heads and faceplates, baseball bats, hockey sticks,fishing, skiing and hiking poles; components and housings for electronicequipment including cell phones, personal digital assistants (PDAs)devices, walkmen, discmen, MP3 players, digital cameras and otherrecording devices; and automotive components including fuel rails,grill-guards; brake or clutch parts, pedals, running boards, spoilers,muffler components, wheels, vehicle frames, structural brackets and thelike. The metallic material layer(s) can be electrodeposited onto theinside or the outside of tubes, barrels, shafts, sticks, bats, rollersor complex parts.

“Bath management”, as used herein means establishing and maintaining theconstancy of the electrolyte during production and includes the bathtemperature, removal of impurities by filtering, continuous additions ofreactants, i.e., using metering pumps. As “bath management” is timeconsuming and costly, plating of parts in a single plating tank using acommon electrolyte (also referred to as the “bath” in this context) isof paramount importance.

It is an object of an embodiment of the invention to use a DC and/orpulse electrodeposition process relying on no pulsing, monopolar pulsingand/or bipolar pulsing in a plating system using a shared electrolyte todeposit the metallic material simultaneously onto several parts in aseries electrical connection. The invention provides microstructuresranging from fine-grained crystalline to coarse-grained crystalline(average size greater than 10 microns) and/or to amorphous structures.In all cases the metallic material is applied to a thickness over alayer cross-section in the deposition direction of at least at least 20microns, and even more preferably at least 50 microns. Overall themetallic material represents at least 5%, preferably 10%, morepreferably 25% and up to 100%, of the total weight of the part/article.

It is within the scope of an embodiment of the invention to expose aplated part to at least one subsequent finishing operation selected fromthe group of grinding, polishing, electroplating including chromiumplating, physical vapor deposition (PVD), chemical vapor deposition(CVD), ion-plating, anodizing, powder coating, painting, and screenprinting.

It is an object of a preferred embodiment of the invention tosimultaneously plate at least two tubular parts, in a series electricalconfiguration in an electroplating system using a shared electrolyte,with excellent consistency in the circumferential coating thickness byrotating each part and obtaining uniform thickness profiles along thelength by suitably employing shielding and current thieving to overallachieve consistent part coating weights, thickness profiles and coatingmicrostructures.

It is an object of an embodiment of the invention to simultaneouslyplate at least two parts, in a series electrical connection orconfiguration in an electroplating system using a shared electrolyte,with uniform or suitably tapered thickness profiles and consistentcoating weights and coating microstructures.

It is an object of a preferred embodiment of the invention tosimultaneously plate at least two parts, in a series electricalconfiguration in an electroplating system using a shared electrolyte,with consistent coating weights with the maximum weight difference ofany part from the average part weight plated at the same time in eachrun being less than ±20%, preferably less than ±10%, and even morepreferably less than ±5% and/or the standard weight deviation per rundivided by the average weight per run of less than ±5%, preferably ±2.5%and even more preferably ±1.5%, and/or in the case of four or moresubstrates a kurtosis per run of ≦10, preferably ≦2.5 and even morepreferably ≦0.

It is an object of a preferred embodiment of the invention tosimultaneously plate at least two parts, in a series electricalconfiguration in an electroplating system using a shared electrolyte,where the electrodepositing parameters are selected so that eachelectrodeposited metallic layer has a thickness ranging from 20 micronsto 5 cm and wherein part-to-part variability obtained is manifested by aratio of maximum layer thickness to average layer thickness of less than±20% and ratio of layer thickness standard deviation to average layerthickness of less than ±20% and in the case of four or more substrates akurtosis of less than 10.

It is an object of a preferred embodiment of the invention tosimultaneously plate at least two parts, in a series electricalconnection in an electroplating apparatus using a shared electrolyte,with consistent coating weights by minimizing shunt current flowsbetween adjacent cells to ensure that the charge measured in coulombs(=A×s) supplied to each part remains uniform.

It is a further object of an embodiment of the invention to provide anapparatus for simultaneously electrodepositing a metallic material ontothe surface of at least two substrates in a series electricalconnection, said apparatus comprising:

(a) an electrolyte well, e.g. a central electrolye well, filled with anelectrolyte solution containing ions of the metallic material to bedeposited;

(b) at least two plating cells, each providing an electrodepositingzone, electrically connected in series and powered by a single powersupply;

(c) an electrolyte circulation loop for supplying said electrolytesolution to each plating cell from the well electrolyte and forreturning said electroplating solution to said electrolyte well;

(d) each plating cell comprising:

-   -   (i) at least one anode,    -   (ii) a cathode capable of receiving and holding one of a        temporary or permanent substrate to be plated optionally        positioned in relation to a thieving electrode,    -   (iii) agitated electrolyte containing ions of metallic material        to be deposited,    -   (iv) means for minimizing voltage differences and shunt currents        between plating cells selected from the group consisting of        divider plates, synchronized power supplies and tortuous        electrolyte circulation pathways,    -   (v) optionally a shield disposed between the anode and the        cathode, the shield being configured to mask between 0 and 90%        of the anode or the cathode.

(e) at least one power source electrically connected to at least twoplating cells.

It is a further object of the invention to provide in an embodiment anapparatus for simultaneously electrodepositing a metallic material ontothe surface of at least four substrates in a series electricalconnection employing at least two power supplies, said apparatuscomprising:

(a) an electrolyte well, e.g. a central electrolyte well, filled with anelectrolyte solution containing ions of the metallic material to bedeposited;

(b) at least two plating cells electrically connected in series;

(c) at least two strings of at least two plating cells each connected inseries;

(d) an electrolyte circulation loop for supplying said electrolytesolution to each plating cell from the electrolyte well and forreturning said electroplating solution to said electrolyte well;

(e) at least two power supplies, each electrically connecting adifferent string of plating cells, where the power supplies aresynchronized with respect to current on time, off time, and reverse timeand the respective current densities at all times during a platingcycle;

(f) each plating cell providing an electrodepositing zone andcomprising:

-   -   (i) at least one anode,    -   (ii) a cathode capable of receiving and holding one of a        temporary or permanent substrate to be plated optionally        positioned in relation to a thieving electrode,    -   (iii) agitating means selected from the group consisting of a        pump, educators, stirrers, air agitation and ultrasonic        agitation for agitating electrolyte solution in the cell,    -   (iv) means for minimizing voltage differences and shunt currents        between plating cells selected from the group consisting of        divider plates, synchronized power supplies and tortuous        electrolyte circulation pathways,    -   (v) optionally a shield disposed between the anode and the        cathode, the shield being configured to mask between 0 and 90%        of the anode or the cathode.

It is a further object of a preferred embodiment of the invention tosimultaneously plate at least two parts, in a series electricalconnection in an electroplating system using a shared electrolyte, withconsistent coating weights by minimizing the number of power suppliesrequired to plate multiple parts and the ratio between the total numberof power supplies used and the total number of parts produced in eachrun is ≦1, preferably ≦½ and even more preferably ≦⅓.

It is a further object of a preferred embodiment of the invention tosimultaneously plate at least four parts, at least two parts each in aseries electrical configuration and at least two sets of at least twoplating cells connected in series simultaneously in an electroplatingsystem using a shared electrolyte.

It is a further objective of the invention to simultaneously plate atleast two parts, each in a series electrical connection in anelectroplating apparatus using a shared electrolyte, with consistentcircumferential thickness profiles between parts by rotating each partto be plated at rotation speeds between 1 and 1,500 RPM againststationary soluble or dimensionally stable anodes.

These objectives are achieved by “series plating” of parts whilemaintaining control (or quasi-control) of the coulombs supplied to eachindividual part. Several “strings” are plated simultaneously byproviding one power supply for each string to control the appropriatecoulomb supply to all parts in a series array in a shared electrolyte.For this purpose all power supply modules are suitably synchronized tominimize cell voltage differences between individual cells in real time,i.e., in the case of using pulse electrodeposition the identical platingschedule is imposed on all parts simultaneously at all times, including,the on times, off times, reverse times and the respective peak forwardcurrent and peak reverse current which can be achieved by controllingall power supply modules from a central power supply control module. Theplating schedule profiles (pulse rise times, fall times) are also keptthe same by using power supplies with similar specifications. To enableutilization of a common electrolyte and maintain control over eachpart's coulomb supply, “shunt currents” between cells/parts areminimized by appropriate use of dividers/baffles and high resistanceionic pathways are provided for the entire electrolyte circulation loop(electrolyte feed, electrolyte overflow, electrolyte recirculation).This is accomplished by maintaining a principal electrolyte wellcontaining a heater, filter, and pump. A tank can be divided intoseveral compartments housing the individual cells which are all sharingthe common electrolyte and as such all cells/zones are ionicallyintercommunicating. Suitable pipes/eductors enable the electrolyte to befed into each cell from a common manifold and each cell is preferablyseparated from the adjacent cell(s) by divider plates. The electrolytein each cell/zone is agitated by means selected from the group of amechanical pump, educators, stirrers, air agitation, ultrasonicagitation, gravity drainage or the like. Each cell typically has its ownweir/electrolyte return flow manifold to enable electrolyterecirculation. The divider plates do not necessarily extend all the wayto the top/bottom of the tank, and all cells are “ionically connected”at the top and/or bottom of the cells, and/or by the electrolyte feedingtubes and electrolyte return channels. The dividers and varioustubes/channels, however, have been designed to sufficiently increase the“ionic resistance” between adjacent cells to provide for tortuouselectrolyte pathways and to behave essentially like “totally ionicallyisolated tanks” as long as the cell operating voltages and therespective electrode potentials between adjacent cells do not vary bymore than a critical amount to enable the achievement of the desiredcoating weight consistency.

Appropriate thickness profiles are achieved by suitably shielding theanodes and, optionally, by employing current thieves.

Conventional electroplating typically involves e.g. rack plating whereinthe parts to be plated are all placed on a suitable “part rack”. In this“parallel plating” configuration all parts are electrically connected toone power supply and the total current to the plating cell can beadjusted to determine the resulting total applied voltage betweenpositive and negative lead busbars. The individual current and thecoulombs supplied to each specific part and the resulting weight of eachindividual part can, however, not be controlled. As the individualcurrent supplied to each part is affected by the ohmic and ionicresistances in this configuration, uniform part weights are onlyachieved if no differences in ohmic and ionic resistances exist in thesystem, which is almost never the case. While this approach is commonlyused in the electroplating industry, and is appropriate for thincoatings where overall coating weight, uniformity and consistency is notan issue and coating weights and thickness can fluctuate by +50% or moreand incompletely coated parts are simply recoated, this approach is notacceptable for structural coatings requiring reproducible and consistentcoating properties. The “parallel plating” approach relies on all partsto be uniform in electrical bulk and surface resistance and connectedequally well to the rack (similar contact resistance) and e.g. anycorroded or otherwise high ohmic resistance connection is avoided, asultimately it is the individual part's potential which controls thecurrent fraction it receives. As illustrated below, polarization curvescorrected for internal resistance losses for typical electroplatingsystems have a very flat slope, i.e. a small change in part potential (afew tens or a few hundred mV) can result in a substantial change incurrent (1 ampere or tens of amperes) and as a result coulombs received,and therefore realized coating weights. To achieve the desired controlusing conventional plating techniques it becomes necessary to plate onepart at the time which is time consuming, uneconomic and, forapplications requiring a large number of parts, impractical.

The above recited objects are obtained by the invention herein (contraryto the case with conventional electroplating) which is directed to amethod of applying a metallic material deposit, comprising the steps ofelectrodepositing a metallic material from an aqueous or non-aqueouselectrolyte in a multi-cell electroplating system sharing a commonelectrolyte with the electrodeposition parameters being average currentdensity ranging from 5 to 10,000 mA/cm²; forward pulse on time rangingfrom 0.1 to 10,000 ms or as provided by DC electrodeposition processing;pulse off time ranging from 0 to 10,000 ms; reverse pulse on timeranging from 0 to 1,000 ms; peak forward current density ranging from 5to 10,000 mA/cm²; peak reverse current density ranging from 5 to 20,000mA/cm² except when reverse pulse on time is zero as then the peakreverse current density is not applicable; frequency ranging from 0 to1000 Hz; a duty cycle ranging from 5 to 100%; working electrode (anodeor cathode) rotation speed ranging from 0 to 1,500 RPM; bath composition(containing metal ions to be plated in a concentration range of 0.01 to20 moles per liter); bath (electrolyte) temperature ranging from 0 to150° C.; bath pH ranging from 0 to 12; bath (electrolyte) agitation rateranging from 1 to 6,000 ml/(min·cm²) anode or cathode area; bath(electrolyte) flow direction at cathode ranging from tangential toincident (i.e. perpendicular); shielding anode(s) by physically coveringbetween 0-95% of the geometrical anode surface area(s); andelectrochemically inert material concentrations in the bath between 0and 70 vol %.

In a series string the anodes and cathodes are electrically connected,i.e. anode of a cell 1 is connected to cathode of a cell 2 and anode ofa cell 2 to cathode of a cell 3 and so forth to enable the simultaneousplating of multiple parts in a series arrangement. Optionally currentthieves are provided to deal with edge effects, optimize thicknessprofiles and the like.

Method herein provides a uniform deposit thickness profiles,microstructures and weights for all parts plated simultaneously. Theelectroplated thickness ranges from 20 microns to 5 cm having preferablya fine grained microstructure with grain size ranging from 2 nm to 5,000nm, a coarse grained microstructure with grain size greater than 5,000nm or an amorphous microstructure and the maximum deposit weightdifference of any parts from the average part weight plated at the sametime in different cells, as well as the maximum ratio between standarddeviation and average weight value are less than +20%, preferably lessthan +10%, preferably less than +5% and more preferably less than +2.5%.

As used herein the terms “product” and “deposit” means deposit layer orfree-standing deposit body.

As used herein, the term “thickness” refers to depth in a depositdirection.

As used herein the term “average cathode current density” (I_(avg))means the “average current density” resulting in depositing the metallicmaterial and is expressed as the means of the cathodic minus the reversecharge, expressed in mA×ms divided by the sum of the on-time, off-timeand reverse time expressed in ms, i.e.,=I_(peak)×t_(on)−T_(reverse)×t_(an))/(t_(on)+t_(an)+t_(off)); where “x”means “multiplied by”.

As used herein the term “forward pulse” means cathodic deposition pulseaffecting the metallic deposit on the work piece and “forward pulse ontime” means the duration of the cathodic deposition pulse expressed inms: t_(on)

As used herein the term “off time” means the duration where no currentpasses expressed in ms: t_(off)

As used herein the term “reverse pulse on time” means the duration ofthe reverse (=anodic) pulse: t_(an)

As used herein “electrode area” means the geometrical surface areaeffectively plated on the work piece which can be a permanent substrateor a temporary cathode expressed in cm².

As used herein the term “peak forward current density” means the currentdensity of the cathodic deposition pulse expressed in mA/cm²: I_(peak)

As used herein the term “peak reverse current density” means the currentdensity of the reverse/anodic pulse expressed in mA/cm²: I_(reverse) orI_(anodic)

As used herein the term “duty cycle” means the cathodic on time dividedby the sum of all times (on time, off time and anodic time (alsoreferred to as reverse pulse on time)).

As used herein the “average” ( χ) is defined as the arithmetic means ofa set of data, e.g., the average weight is the arithmetic means of a setof weight data.

In statistics, the variance of a random variable, probabilitydistribution, or sample is one measure of statistical dispersion,averaging the squared distance of its possible values from the expectedvalue. Whereas the mean is a way to describe the location of adistribution, the variance is a way to capture its scale or degree ofbeing spread out. The “standard deviation”, is the square root of thevariance and, as it has the same units as the original variable, it iscommonly used to interpret the consistency of data. As used herein, the“standard deviation” (σ) is the root mean square deviation of valuesfrom their arithmetic mean according to the following formula:

$\sigma = \sqrt{\frac{\sum\left( {x - \overset{\_}{x}} \right)^{2}}{\left( {n - 1} \right)}}$

wherein χ is the sample arithmetic average and n is the sample size.

As used herein the “kurtosis” of a data set characterizes the relativepeakedness or flatness of a distribution compared with the normaldistribution. Kurtosis is defined as the fourth cumulant divided by thesquare of the variance of the probability distribution. A positivesample kurtosis indicates a relatively peaked distribution of a set ofdata whereas a negative sample kurtosis indicates a relatively flatdistribution of the data set. Higher kurtosis means more of the varianceis due to infrequent extreme deviations, as opposed to frequentmodestly-sized deviations. Kurtosis (G) is defined as:

$G = {\left\{ {\frac{n\left( {n + 1} \right)}{\left( {n - 1} \right)\left( {n - 2} \right)\left( {n - 3} \right)}{\sum\left( \frac{x_{i} - \overset{\_}{x}}{\sigma} \right)^{4}}} \right\} - \frac{3\left( {n - 1} \right)^{2}}{\left( {n - 2} \right)\left( {n - 3} \right)}}$

wherein x_(i) is the i^(th) value, and χ is the sample arithmeticaverage, n is the sample size and σ is the standard deviation.

As used herein minimum or maximum “weight difference” expressed inpercent is the observed minimum or maximum value of each run or data setdivided by the average weight of the data set multiplied by 100.

As used herein “percent weight deviation” is the standard weightdeviation of each run divided by the average weight of said runmultiplied by 100 expressed as “STDEV/Average Weight [%]” in theexamples.

As used herein the term “chemical composition” means chemicalcomposition of the electrodeposited material.

As used herein “electroplating zone” and “plating cell” means a single“plating unit” comprised of an anode and a cathode immersed in theplating bath. The multi-cell plating system contains a number ofcells/zones and all cells/zones share a common electrolyte.

As used herein “shielding” of anodes involves shielding from 0 to 95% ofthe anode geometrical area using, e.g., a polypropylene sheet or otherelectrolyte impermeable foil or membrane to effect local currentdensities and deposit thicknesses, as required. As the person skilled inthe art will know, shielding increases the voltage drop between theelectrodes and hence for the same current the cell voltage increaseswith the level of shielding.

As used herein “thieving” of a work piece entails attaching an auxiliarycathode to the work piece to redirect part of the current away from thepart to be plated to achieve a desired property, i.e., frequently adesired thickness profile at or near edges of parts.

As used herein “string of cells” means several individual plating cellsare electrically connected in a series string by connecting the anode ofone cell to the cathode of the following cell, the anode of thefollowing cell is connected to the cathode of the next cell and so forthso that the sum of the individual cell voltages of all the cellsconnected in series is equal to the applied string voltage.

As used herein “shunt currents” refers to “leakage currents” whichdevelop between working electrodes, i.e. the electrodes where thedesired electrochemical reaction takes place, located in differentelectroplating zones/cells when said electrodes are immersed in a commonelectrolyte. In the case of a plurality of electrochemical cells whichshare a common electrolyte, the electrolyte serves as ionic conductorthrough which shunt currents flow between electrodes located indifferent cells. Such shunt currents “short-circuit” cells through thecommon electrolyte and, if not minimized, i.e., by maximizing the ionicresistance between adjacent cells, can prevent the effective andefficient operation of a set of cells and negate control over theplating current flow and the resulting plating weights. Shunt currentscan also flow under open circuit conditions, when no external power isprovided to or drawn from the cells and can result in uneven and/orundesired plating of electrodes as well as corrosion reactions. Tominimize shunt currents between electrodes in different cells,electrolytes must be conducted to, through and from the cells byproviding separate or tortuous electrolyte pathways to each cell inorder to increase the ionic resistance between interconnected cellsthereby minimizing the flow of shunt currents.

As used herein “synchronizing” power supplies means that all powersupplies used to supply current to parts or series strings of parts arecontrolled, i.e., by a central control unit, to ensure that currentssupplied to all cells at all times are similar to equal, i.e., in thecase where a stepped DC current profile is used, the current is steppedfrom one level to the next at the same time by “synchronized powersupplies” and in the case of pulse electrodeposition, the timing andheight of on-pulses and reverse pulses, as well as the off times, aresimilar to equal at all times during the plating cycle. Synchronizingpower supplies ensures that the current ramps up or declinessimultaneously in all cells and, in case of pulsing, on times, off timesand reverse times are synchronized to minimize electrode potential/cellvoltage differences between cells and the generation of “shuntcurrents”.

As used herein “parallel plating” means that one or more anodes in aplating cell holding the electrolyte are electrically connected witheach other, two or more cathodes/work pieces/parts to be plated areelectrically connected with each other and a power supply is used withone lead attached to supply power to all parallel connected anodes andthe other power supply lead is attached to all parallel connected partssubmersed in the electrolyte. Parallel connected cells and/or parallelconnected parts share the same applied voltage; the actual cell or partcurrent and coulombs per part can vary depending on a number of cellvariables.

As used herein “series plating” means that one lead of the power supplyis electrically connected to an anode in one cell, the cathode of saidcell is electrically connected to the anode in another cell, the cathodein that other cell is connected to an anode in yet another cell and soforth until the last cathode is connected to the other lead of thesupply power to close the electrical circuit. “Series plating” asdefined herein also involves all electrodes being submersed in a commonelectrolyte. If no shunt currents exist, series connected cells allshare the same current and coulombs, the cell voltage, however, may varyfrom cell to cell depending on a number of cell variables. The sum ofall individual cell voltages connected in series is equal to the totalapplied voltage required to maintain the desired current, while thecurrent flowing through each cell remains the same. “Series plating” isachieved by a “series connection” of the appropriate electroplatingzones/cells.

As the weight of a coating is controlled by the current multiplied bythe plating time (the “charge” measured in coulombs) and the efficiencyof the reaction, consistent weights can best be achieved by platingparts with a dedicated power supply for each plating cell or by usingone power supply and connecting all cells in a series arrangement. Thisis always achieved if each plating cell is totally independent andcontains its own electrolyte, i.e., electrolyte is not shared by theindividual cells. If plating cells share a common electrolyte, “shuntcurrents” are formed between adjacent cells and the coulombs directed toeach cathode/work piece can no longer be precisely controlled.Conditions are complicated further if a two or more cells sharing acommon electrolyte are connected in series to form a “string of cells”and the multi-compartment plating system also contains a number of“strings of cells” operated at the same time.

In summary, the invention teaches the simultaneous plating of multipleparts/workpieces in a multi-compartment plating cell using a commonelectrolyte with tight part thickness profile and weight tolerances byemploying series plating and minimizing shunt current effects at maximumapplied voltages (V_(max)) of up to 50V and achieving and maintainingthe desired excellent part weight and thickness consistency. To achievethe desired part consistency the plating parameters in each cellincluding average current density I_(average), peak current densityI_(peak), reverse (or anodic) current density I_(anodic), on time, offtime, anodic time (also referred to as reverse pulse on time),frequency, duty cycle, work piece rotation rate, agitation and flowrate, shielding, temperature, pH, bath (electrolyte) composition andparticulate content in the electrolyte and overall plating time, arekept the same in all plating cells. Specifically, as will beillustrated, selected electrical parameters including the on, off andreverse times as well as the peak forward and reverse current must besynchronized between individual series strings. This is achieved bycontrolling all power supplies from a central computer and imprintingidentical plating schedules on all strings and initiating andterminating the plating of all strings simultaneously. If all theseconditions are maintained, the resulting deposit properties of platedparts, regardless of the cell position they are plated in or formed in,including grain size, hardness, yield strength, Young's modulus,resilience, elastic limit, ductility, internal and residual stress,stiffness, chemical composition, thermal expansion, electricalconductivity, magnetic coercive force, thickness and corrosionresistance, are kept essentially the same on all parts. The teachingsprovided are also illustrated in the working examples below.

In the case of metal matrix composites (MMCs) the desired volumeparticulate content in the metallic layer is obtained by inert materialadditions to the electrolyte. Minimum electrochemically inertparticulate concentrations suspended in the bath (electrolyte) can be,for example, 0%, 5% or 10% by volume (vol %). As only particulatesuspended in the electrolyte and contacting the cathode will beincorporated into the deposit, agitation rate and flow direction can beused as suitable parameters to adjust the particulate content in thebath (electrolyte) and therefore in the deposit. Maximumelectrochemically inert particulate concentration suspended in the bath(electrolyte) can be, for example, 50, 75 or 95 vol % to affect aparticulate content in the deposit ranging from 0 to 95% by volume. Thehigher the particulate contents in the electrolyte between anode andcathode, the higher the ionic resistance and the higher the cell voltagerequired to pass the desired current.

In the case of metal matrix composites, particulate particle size,particulate shape and particulate chemistry are adjusted by inertmaterial additions to the electrolyte.

Selecting the appropriate average cathodic current density and the peakforward current density and peak reverse current density enablesachieving the appropriate microstructure (average grain size oramorphous deposit), as well as alloy and metal matrix composition.Increasing average and peak forward current densities typically cause adecrease in grain size.

Adjusting the forward pulse on time, off time and anodic time (reversepulse on time) can be used to vary the grain size, amount of alloy andmetal matrix in a deposit. Increasing the on time usually increasesgrain size, increasing the off time usually results in decreasing grainsize and increasing the anodic time usually increases grain size.

Duty cycle, cathode rotation speed, bath composition, pH and agitationrate can be suitably adjusted to achieve the desired grain size, alloyand metal matrix composition.

In summary, suitable electrodeposit properties can be obtained bysuitably adjusting electrodeposition parameters (conditions) during thecourse of electrodeposition to produce desired thickness profiles andmaterial properties to satisfy requirements for many modern components.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a cutaway top view of a multi-cell compartment.

FIG. 1A is an enlarged view of two adjacent cells of FIG. 1.

FIG. 2 depicts the electrical wiring schematic for simultaneouslyplating 18 parts in an 18 cell multi-cell compartment, i.e. compartmentB1 of FIG. 1, configured to simultaneously plate six strings, eachstring containing three parts in a series configuration.

FIG. 3 illustrates voltage-current profiles for a number of workpiecesin a plating cell.

FIG. 4 illustrates voltage-current profiles for workpieces at variouscoating levels in a plating cell for DC plating.

FIG. 5 illustrates voltage-current profiles for workpieces at variouscoating levels for pulse electrodepositing.

FIG. 6 illustrates voltage-time profiles for 3-part and 4-part seriesplating strings.

FIG. 7 illustrates voltage-time profiles for six 3-part strings ofgraphite/epoxy tubes using a three-step plating profile.

FIG. 8 illustrates coating thickness profiles for parts plated in asingle cell and parts plated in a multi-cell plating system, i.e.provides a single cell tank and a multi-cell tank thickness profilecomparison.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS OF THE DISCLOSURE

As indicated above apparatus for the invention includes a plurality ofplating cells electrically connected in series employing one powersupply for two or more plating cells.

Each plating cell constitutes an electrodepositing zone and has one ormore anodes and one or more cathodes and contains an aqueous electrolytebath containing ions of metallic material to be deposited. Thecathode(s) and anode(s) are connected to a source of D.C. or pulsingcurrent which is provided by a suitable power supply. Electrodepositionoccurs on the cathode.

Each plating tank or plating cell is equipped with a fluid circulationsystem.

The anode can be dimensionally stable, e.g. of platinum or graphite, orcan be a soluble anode that serves as a source of material to bedeposited.

In the case of a free-standing deposit, the cathode is fabricated from amaterial that facilitates deposit stripping, e.g. titanium and graphite,and can be reusable providing for a temporary substrate.

In the case of deposit as a layer or coating, the cathode is metal,suitably metalized plastic (polymer) or other material as described andis therefore used as a permanent substrate.

The process of the invention comprises the steps of providing amulti-cell, and optionally a multi-compartment, plating systemcontaining a common (shared) electrolyte. For example, compartments aresubdivided into individual plating cells. Each plating cell contains twoworking electrodes, namely an anode and a cathode, and adjacent platingcells are separated from each other by a divider wall to reduce shuntcurrents. The plating system includes an electrolyte circulation system,i.e., advantageously the electrolyte is pumped from a centralelectrolyte well through suitable piping into each plating cell. Care istaken, e.g., through the use of educators, that the electrolyte volumeand the electrolyte flow speed is kept uniform across all cells.Electrolyte return flow can be provided through overflow outlets andmanifolding preferably using an approach where the fluid flow isinterrupted into drops to disrupt the ionic continuity of theelectrolyte flow thereby further minimizing effects of shunt currents.The electrolyte circulation loop preferably also contains a singlefilter or multiple suitable filters to remove impurities and dirt. Aworkpiece is loaded into each cell, i.e. using a suitable loading toolto enable simultaneous insertion of multiple work pieces into multiplecells at a time. The workpieces to be coated are either inherentlyconductive or suitably rendered conductive. Electrical connections areprovided to a string of cathodes/work pieces to be plated and to anappropriate number of anodes, and electroplating of the desired metallicmaterial with a predetermined microstructure and composition on at leastpart of the external surface of all cathodes takes place. Parts to beplated simultaneously in series strings using direct current or pulsedcurrent, as described in greater detail above or below, produceelectrodeposits with consistent properties. Plating cell designsminimizing shunt currents are used and all power supplies are suitablysynchronized to maintain uniform part weights, thickness profiles andmicrostructures meeting tight production specifications.

Ranges for cathodic current density, forward pulse on time, off time,reverse (anodic) pulse on time, peak forward current density, peakreverse current density, duty cycle, electrode rotation speed, bath(electrolyte) temperature, bath (electrolyte) composition, bath(electrolyte) agitation rate, shielding and inert additions are givenabove.

Typical electroplating cell voltages range from 2 to 30V per cell andnumerous cells are electrically connected in series. For safety reasonsthe overall string voltages are preferably kept at ≦50 Volts. Typically,each three cells are associated in a string with the cells in a stringbeing electrically interconnected in series with each string beingsupplemented with power from a single power source.

We turn now in more detail to the process parameters.

All electrical parameters for a string, i.e. cathodic current density,forward pulse on time, off time, reverse pulse on time, peak forwardcurrent density, peak reverse current density, duty cycle and frequencyare adjusted using the power supply for the string.

Where electrode rotation is required, rotation is achieved, e.g., byusing a fixer or a variable speed motor coupled to the cathode to enableits rotation. One motor is typically used to rotate a number ofworkpieces by employing gear or belt drives.

The bath (electrolyte) temperature can be controlled by one or severalheaters, i.e., immersion heaters. In the case of larger systems,resistance heating during plating requires insertion of a chiller tokeep the electrolyte temperature from rising beyond a set maximumtemperature. Heaters and chillers are preferably located in the centralelectrolyte well.

Bath (electrolyte) composition can be maintained by one or more stepscomprising using a metering pump to add solution; adding, removing ormodifying selected components using a circulation/bypass loop; usingsoluble anode with anodic current control to supply ionic species; usingsoluble anode and a dimensionally stable anode; using two or moresoluble anodes of different composition with individual current controlin the case of alloy deposit; air agitation to selectively oxidize bathcomponent(s); agitation to control particulate contents; and mixing toeffect local ion concentration(s) at the cathode surface. The bathcontains metal ions to be plated in a concentration ranging, forexample, from 0.01 mole per liter to 20 moles per liter.

The bath (electrolyte) agitation rate in each cell is controlled bysuitably adjusting pump speed, flow direction and the use of eductors.

The bath (electrolyte) pH is controlled by addition of acid or base, asappropriate to lower or raise the level as appropriate to maintain thedesired pH range.

Various property parameters of the electrodeposited layers are listedbelow.

Minimum thickness of the electrodeposit [μm]: 20; 30; 50

Maximum thickness of the electrodeposit [mm]: 5; 25; 50;

Minimum thickness of a fine-grained sublayer [nm]: 1.5; 25; 50

Maximum thickness of a fine-grained sublayer [μm]: 50, 250, 500

Minimum average grain size [nm]: 2; 5; amorphous (i.e. no grains butglassy structures)

Maximum average grain size [nm]: 250; 500; 1,000; 5,000; 10,000; 250,000

Minimum stress of the sublayer or the electrodeposited layer (in tensionor compression) [ksi]: 0; 1; 5

Maximum stress of the sublayer or the electrodeposited layer (in tensionor compression) [ksi]: 25; 50; 200

Minimum ductility of the electrodeposit [% elongation in tension]: 0.5;1; 2.5

Maximum ductility of the electrodeposit [% elongation in tension]: 5;15; 30

Hardness [VHN]: 50-2,000

Yield strength [MPa]: 100-3,000

Young's modulus [MPa]; 50-300

Resilience [MPa]: 0.25-25

elastic range [%]: 0.25-2.5,

coefficient of thermal expansion [ppm/K]:0-50

coefficient of friction: 0.01-1

electrical resistivity [micro Ohm-cm]: 1-100

Deposition rates used are at least 0.001 mm/hr, preferably at least 0.01mm/hr and more preferably at least 0.10 mm/hr.

As used herein, the term “deposit direction” means the direction ofcurrent flow between anode and cathode in the electrodepositing cell andthe resulting build-up in the electrodeposited layer on the cathode, andif the cathode is a flat plate, the direction of deposit isperpendicular to the cathode.

We turn now to the metallic materials that are electrodeposited.

In one case the metallic material is a metal selected from the groupconsisting of Ag, Au, Cu, Co, Cr, Mo, Ni, Sn, Fe, Pd, Pb, Pt, Rh, Ru andZn.

In another case the metallic material is an alloy of one or moreelements selected from the group consisting of Ag, Au, Cu, Co, Cr, Mo,Ni, Sn, Fe, Pd, Pb, Pt, Rh, Ru and Zn and optionally one or moreelements selected from the group consisting of B, P, C, S and W.

In still another case, the metallic material contains:

(i) one or more metals selected from the group consisting of Ag, Au, Cu,Co, Cr, Mo, Ni, Sn, Fe, Pd, Pb, Pt, Rh, Ru and Zn;

(ii) at least one element selected from the group consisting of C, O andS; and

(iii) optionally at least one or more elements selected from the groupconsisting of B, P and W. Group (ii) elements are provided in the rangeof 10 ppm to 5%, group (iii) elements in the range of 500 ppm to 25%,the balance being group (i) elements which typically range from 75% to99.9%.

We turn to a case where the electrodeposit is a metallic materialcontaining particulates, i.e., of metal matrix composite. The metallicmaterial is as described above. Suitable particulate additives forpreparing metal matrix composites include metal (Ag, Al, Cu, In, Mg, Si,Sn, Pt, Ti, V, W, Zn) powders; metal alloy powders; metal oxide powdersof Al, Co, Cu, In, Mg, Ni, Si, Sn, V and Zn; nitrides of Al, B and Si;carbon (graphite powder, carbon powder, graphite fibers, Buckminsterfullerenes, carbon nanotubes, diamond); carbides of B, Cr, Bi, Si, W;glass, organic materials including polymers such aspolytetrafluoroethylene, polyethylene, polypropylene,acrylonitrile-butadiene-styrene copolymer, polyvinyl chloride, epoxyresins. The particulate average particle size is typically below 10,000nm (10 μm), more preferably, below 500 μm, still more preferably below100 μm.

In the case where product contains particulates, the particulates arepart of the plating bath and are deposited with the metallic material.In other words, metal matrix composites are electrodeposited. Theparticulate components do not participate in electrochemical reductionas is the case with the metallic components and simply get incorporatedinto the electrodeposited deposit by inclusion. The volume content ofparticulates can be suitably adjusted by adding particulates to the bathto affect the incorporation of said particulate into the electrodeposit.Agitation rates and/or flow patterns can be used to control the amountof particulates suspended in the bath, with higher agitation ratesgenerally resulting in increased particulate contents in the deposits.

We turn now to where the electrodeposit is for a free-standing form. Thefree-standing form is stripped from strippable cathode such as atitanium cathode as described above. The utility of free-standing formis, for example, for electroformed articles such as foils, plates, tubesand complex shaped articles.

We turn now to where the electrodeposit is as a layer or coating on asubstrate. In this case the permanent substrate (substrate stays withthe electrodeposit to form an article containing the electrodeposit andsubstrate, rather than being a strippable substrate) is the cathode.

Suitable permanent substrates include a variety of metal substrates(e.g. all steels; metals and alloys of Al, Cu, Co, Ni, Fe, Mo, Pt, Ti, Wand Zr), carbon-based materials (e.g. carbon, diamond, graphite,graphite fibers and carbon nanotubes) substrates; and polymersubstrates. Suitable polymeric materials for polymeric substratesinclude filled epoxy resin composite material, unfilled epoxy resin,polyamide, mineral filled polyamide resin composites, polyvinyl chloride(PVC), thermoplastic polyolefins (TPOs), polytetrafluoroethylene (PTFE),polycarbonate and acrylonitrile-butadiene-styrene (ABS). Suitablefillers for the filled epoxy resin composites include glass fibers,carbon, carbon nanotubes, graphite, graphite fibers, metals, metalalloys, ceramics and mineral fillers such as talc, calcium silicate,silica, calcium carbonate, alumina, titanium dioxide, ferrite, and mixedsilicates (e.g. bentonite or pumice), and are present in amount up to70% by weight. Mineral-filled polyamide resin contains powdered (e.g.0.2-20 microns) mineral fillers such as talc, calcium silicate, silica,calcium carbonate, alumina, titanium dioxide, ferrite and mixedsilicates (e.g. bentonite or pumice) and mineral contents of up to about40% by weight and provides high strength at relatively low cost.

Where the substrate to be provided with an electrodeposited layer orcoating is poorly conductive or nonconductive, it can be metalized torender it sufficiently conductive for plating, e.g. by applying a thinlayer of conductive material, e.g. by electroless deposition, PVD, CVDor by applying an electrically conductive paint. Thus the subjectinvention encompasses providing layer or coating to virtually anysubstrate material.

An electrodeposited coating layer can be suitably exposed to a finishingtreatment, which can include, among others, electroplating, i.e.,chromium plating and applying a polymeric material, i.e., a paint oradhesive.

We turn now to benefits of and utility for the invention.

It is noted that the invention requires a multi-cell plating systemsubdivided into multiple individual plating cells containing a sharedelectrolyte with multiple parts plated simultaneously in a seriesplating system with a single power source powering a plurality ofplating cells with excellent metallic layer thickness profile and weightconsistency. Benefits of this include reducing the operating cost of theplating tank, minimizing the plating system floor space and reducing thecapital equipment cost of the plating system and the power supplies aseach power supply provides power to several cells in a seriesconnection. Loading and unloading of parts is typically also done by theemploy of suitable tools, each tool holding multiple parts to be plated.

Electrodeposited metallic materials containing at least in part afine-grained, a coarse grained or an amorphous microstructure providethe desired overall mechanical properties. Compared to conventionallycoarse-grained (average grain size>20 microns) deposits, fine-graineddeposits of the same chemistry provide high hardness (high wearresistance), higher yield strength, and tensile strength. High ductilityand improved corrosion performance is usually provided by coarse-grainedmetallic deposits. Amorphous deposits provide high hardness, high wearresistance and they lack intergranular corrosion and are characterizedby much reduced ductility.

Numerous applications benefit from the multi-cell plating systememploying plating cells electrically connected in series and a singlepower source for each string of cells. As an example, articles such asmetal plated carbon fiber/epoxy rollers, golf shafts, baseball bats,rods, tubes etc requiring a uniform thickness across the cross section,a predetermined thickness profile along the length axis, uniform weightof the parts and metallic layer properties including a high resilience,high outer surface hardness to reduce wear, are produced economically inhigh volume in such a multi-cell plating system.

Parts made from or coated with electrodeposited metallic materials,which are in whole or in part fine-grained, coarse grained and/oramorphous, made by the invention as disclosed herein, are particularlyuseful for structural components requiring great dimensional stabilityover a wide operating temperature range and are not prone to cracking,spalling or delamination. The electrodeposition process herein isparticularly suitable for synthesizing stiff, strong, tough, ductile,lightweight, wear and corrosion resistant free-standing parts, coatingsand layers.

In a number of applications, e.g. the aerospace field, the dimensionalstability of articles with critical dimensions which do not change overthe operating temperature range, are vital. Among metals and alloysselected, nickel-iron alloys (e.g. Invar®, an alloy containing about 36%by weight of nickel and 64% by weight of iron) provide unusually lowcoefficients of thermal expansion (CTE). This invention enables theconvenient and consistent fabrication of articles economically in highvolume using CTE matching by providing the added strength through agrain refinement.

Articles made using the multi-cell electroplating system described finduse in a variety of applications requiring durable, light-weight,high-strength layers or coatings that provide improved reliability,durability and performance characteristics. Applications includeautomotive components, aerospace parts, defense parts, consumerproducts, medical components and sporting goods. Suitable industrialparts include, among others, rods, rolls, tubes or shafts used, e.g., inindustrial applications such as in continuous-process manufacturingequipment, hydraulic equipment and the like; sporting goods such as skiand hiking poles, fishing rods, golf club shafts, hockey sticks,lacrosse sticks, baseball/softball bats, bicycle frames; plates such asgolf club head face plates; as well as complex shapes such as sportsracquets (tennis, racquetball, squash and the like), golf club heads,automotive parts such as grill-guards; running boards; spoilers; mufflertips, wheels, vehicle frames, structural brackets, and carbon fibercomposite (CFC) molds. Consumer products include electronic appliancessuch as walkman, discman, MP3 players, cell phones and blackberries,cameras and other image recording devices as well as TVs. Parts are atleast partially coated on or within their structure to contain variableproperty metallic materials by the invention herein. For example,electrodepositing can be onto a substrate of an orthopedic prosthesis,gun barrel, mold, sporting good or automotive component.

The examples herein illustrate the following plating issues: parallelplating of multiple parts (Prior Art Example 1) with fine-grained Ni orNi—Fe, polarization curves for anodic Ni dissolution and cathodic Nideposition in different plating cells and using various parts(Background Examples 1, 2 and 3), comparison of coating weightconsistency between a single cell plating one part at a time and amulti-cell plating system plating 18 parts simultaneously. (WorkingExample I), series plating comparison between 3-part and 4-part strings(Working Example II), thickness distribution comparison between a singlecell plating one part at a time and a multi-cell plating system plating18 parts simultaneously (Working Example III), statistical partthickness and part weight analysis in a multi-cell plating systemplating 18 parts simultaneously (Working Example IV), statistical partweight analysis of several runs performed in a multi-cell plating systemplating 18 parts simultaneously (Working Example V), statistical partthickness and part weight analysis of several runs performed in amulti-cell plating system plating 36 parts simultaneously (WorkingExample VI), relationship between part weight variation and cell-to-cellvoltage variation in a multi-cell system plating system (Working ExampleVII).

In a use of the invention herein there is provided crystalline and/oramorphous metallic layers to provide benefits of overall mechanical andchemical properties which are consistent from part to part.

By one case the invention herein metallic coating can be applied to apart made substantially of the same chemistry to achieve excellentmetallurgical bonding between a coating or layer and a substrate andalso refined grain size toward outer surface to enhance a physicalproperty selected from the group of lubricity, hardness, strength,toughness and wear resistance.

In one alternative, the invention herein provides articles with variedgrain sizes, internal stresses and/or brittleness that do not crackand/or delaminate from a permanent substrate during preparation,temperature cycling or regular use.

In one alternative, the invention herein provides articles withfine-grained or coarse grained grain sizes that are strong, tough, hardand wear and abrasion resistant as well as lightweight.

In an alternative, the invention herein provides metal, metal alloy ormetal matrix composite coatings or layers with fine-grained orcoarse-grained grain sizes and/or amorphous microstructures) to enhanceat least one property selected from the group consisting of internalstress, strength, hardness, toughness, ductility, coefficient offriction, scratch resistance and wear resistance due to suitablyselecting the appropriate metallic layer microstructure.

In an alternative, the invention herein provides articles and coatingswith particulate matter therein to effect a deposition of a metal matrixcomposite to achieve metallic layers containing a suitable volumefraction of particulates to, e.g., enhance wear performance.

In another alternative, the invention is used to provide metalliccoatings of metal and/or metal alloy and/or metal matrix composite onthe inside or outside of a tube, e.g., gun barrels using ananocrystalline-NiW-diamond composite or nanocrystalline CoP-diamondmetal matrix composite to improve resistance to cracking, spalling anderosive wear, particularly near the chamber as part of a variableproperty layer that remains hard, wear resistant and of maximumobtainable thermal stability, throughout the service life, along with athermal shock response that is close to that of the steel substratebarrel inner surface (matching coefficient of thermal expansion, Young'smodulus, strength and ductility).

In an alternative, the invention herein provides metallic coatings whichare lubricious for use as sliding surfaces of selected parts, i.e. tohydraulic components or sliding mechanisms of parts such as actions ofautomated and semi-automated rifles with metal, alloy or metal matrixgrades, e.g. metal matrix composites with nanocrystalline NiW layerscontaining hexagonal BN particulates or nanocrystalline-CoP-layerscontaining hexagonal BN particulate inclusions also containing diamondparticulates, to improve the coefficient of friction of said outersurface as well as wear performance and longevity of said outer surface.

The instant invention provides for metallic coatings, layers orfree-standing articles for applications including, for example, sportinggoods (golf clubs and shafts, hockey sticks, baseball bats, tennisracquets, skiing and snowboarding equipment, boards and coatings oncomplex shapes, e.g. skate boards), medical devices (surgery tools,stents, orthopedic prosthesis parts and hp implants), automotive andaerospace applications, consumer products (electronic equipment, phones,toys, appliances, tools), commercial parts (gun barrels, molds).

In a subsequent step, parts containing the metallic coatings or layerscan be subjected to other finishing operations as required including,but not limited to, polishing, waxing, painting, plating i.e.Cr-plating.

According to one alternative of this invention, patches or sections canbe formed on selected areas of articles, without the need to coat theentire article, e.g., utilizing selective deposition techniques.

We turn now to cases where electrodeposits on a plurality of parts areprovided with the same variable property in every one of thesimultaneously plated parts, in the deposit direction and/or within(i.e. along the width or length of) the deposit, i.e., electrodepositingparameters for each cell are modulated the same to cause variation in adeposit on a substrate by more than 10%.

In this case the properties of the electrodeposit are changed bymodulating the deposition parameters (i.e. the electrical platingconditions) to vary grain size and therefore properties influenced bythe grain size including, but not limited to, hardness, yield strengthand resilience, the same in all the parts. This is described in U.S.application Ser. No. 12/003,224, filed 20 Dec. 2007, for single cellelectro deposit.

Grading in the deposition direction or multidimensional grading isparticularly suitable if, an article without a fine grained layerexhibits significant internal stress and/or brittleness and whenmetallic material applied as a coating or layer cracks and/ordelaminates from a substrate and in the case of free standing structureswhich crack and/or disintegrate upon forming or deforming in use (i.e.upon bending or when under tension).

Grading in the deposition direction or multidimensional grading can becarried out, for example, in each electrolytic cell as previouslydescribed equipped with a recirculation loop with means to enablevariation of flow rate so as to provide different bath composition as afunction of distance from the center of the deposit thereby gradingthroughout a coating grade. Other ways of carrying this out includeanode shielding, and/or placing one of the several anodes in closerproximity to an area to be varied in property.

Turning again to where operating parameters are modulated to producemicrostructures with different grain sizes, this is illustrated fornickel in Table 1 below.

TABLE 1 Variation in Properties of Nickel Due to Variation in GrainSize. 20 nm 100 nm 30 micron grain size grain-size grain size Hardness[VHN] 600 325 120 Elongation in tension [%] 2 16.7 30 Yield Strength[MPa] 850 670 150 Young's Modulus [GPA] 150 200 200 Modulus ofResilience [GPA] 2.4 1.1 0.06

Further explanation of how changing grain size of nickel affectsphysical properties follows: the hardness increases from 120 VHN (forconventional grain sizes greater than 5 microns) to 325 VHN (grain sizeof 100 nm) and ultimately to 600 VHN (grain size 20 nm) and the yieldstrength from 150 MPa to 850 MPa.

As highlighted, the principal subject of the invention is the employ ofa multi-cell electroplating system using a common electrolyte and powerfrom a single source for multiple cells for electroplating a number ofparts simultaneously in a series arrangement with the objective toconsistently achieve substantially uniform plating thickness profilesand plating weights. The system includes an electroplating solutioncirculated throughout the multi-cell plating tank containing at leasttwo cells, preferably with each power source supplying at least twocells. The following description is based on a plating system containinga central electrolyte well and being readily accessible for performingbath management functions.

A preferred multi-cell plating system and operation thereof is nowdescribed in conjunction with FIGS. 1, 1A and 2.

With continuing reference to FIGS. 1 and 1A, a multi-cell plating system13 is depicted. In system 13, four compartments, B1, B2, B3 and B4,extend from a central electrolyte well A along the length of the platingsystem. Each compartment B1, B2, B3 and B4 is subdivided bydividers/spacers 11 into 18 individual plating cells. The cells for B1are denoted B1-1 to B1-18. The cells for B2 are denoted B2-1 to B2-18.The cells for B3 are denoted B3-1 to B3-18. The cells for B4 are denotedB4-1 to B4-18. Some cells are not depicted and are represented by breaklines. Only cells B1-1, B1′-2, B1-3, B1-4, B1-5, B1-6 and B1-6 and 18are depicted with details (anodes, cathode workpieces, electrolyte inletlines, and electrolyte outlet lines) which are described later.Manifolds for electrolyte distribution and return are depicted for B1and will be described later. Inlet and outlet manifolds for B2, B3 andB4 are omitted from depiction in FIG. 1 to simplify the drawing.Division of each of the compartments into 18 cells enables thesimultaneous plating of up to 72 parts at one time. Depending on needs,the number of compositions can be increased or decreased to one or morecompartments, as required. Similarly, the number of cells percompartment can be suitably increased or decreased (to no less than twocells) to meet part production requirements.

The multi-cell plating system 13 has a central well A for holdingelectrolyte for operation is filled with an electrolyte solutioncontaining ions of the metallic material to be deposited (referred to asan electrolyte bath), containing heater(s) 15, chillers 17 andtemperature sensors (not depicted). Metering pumps (not depicted)suitably dispense chemicals to maintain the electrolyte bath compositionand pH with set specification. Electrolyte is drawn from well A by pump19 and is pumped through a filter 21 to remove impurities and from thereto feed manifold 23 into one of the 18 multi-cell compartments extendingfrom the electrolyte wells to the opposite end of the compartment.

To supply electrolyte to each compartment suitable electrolyte feedpiping is provided, i.e., along the floor of the compartments (referencenumeral 23 for compartment B1) with nozzles (25) at periodic intervalsto direct electrolyte flow into each of the plating cells with the flowdirected upwards, or as desired/required. Electrolyte enters each cellvia a nozzle (eductor) (25) from the pipe (23). The electrolyte supplymanifold is sized appropriately to maintain sufficient pressure toensure that the electrolyte flow into each cell is similar. Atpredetermined locations in each cell height-adjustable openings (27) areprovided to effect electrolyte back flow via a return manifold (29)which discharges the electrolyte back into the central well (A)completing the electrolyte circulation loop. In the system illustrated,the backflow is directed through the container wall to a manifold systemwhich collects the electrolyte from each cell and re-circulates it tothe central electrolyte well. Care is taken in the design of theelectrolyte circulation system to minimize shunt currents between cellsand to enable the plating of uniform parts. The electrolyte circulationhardware is replicated for all other compartments (not shown in FIG. 1).An enlarged view showing elements 23, 25, 27, 29, 31 and 33 in adjacentcells B1-2 and B1-3 is provided in FIG. 1A.

Although electrolyte solution is permitted to flow between cells and allcells share a common electrolyte, by suitably sizing the plumbing andinserting divider plates (11) between cells as described, the ionicresistance between an anode (31) (see FIG. 1A) and cathode (workpiece33) in cell B1-2 or in cell B1-3 is much lower than the ionic resistancebetween anodes and cathodes across adjacent cells, e.g., between anode31 in cell B1-2 and cathode 33 in cell B1-3 and between anode 31 in B1-3and cathode 33 in B1-2. The ionic resistance between anodes and cathodesincreases as the physical distance increases; i.e., the most notableeffects are between anodes and cathodes in directly adjacent cells,followed by anodes and cathodes in cells with one cell in between,followed by anodes and cathodes in cells with two cells in between andso forth. Thus, stray currents between individual cells are reduced asoutlined below.

As shown in FIG. 1A, each plating cell contains an anode (31),preferably a Ti anode basket capable of receiving the soluble anodematerial such as Ni-rounds, and a cathode/work piece (33). If desired,anodes are suitably shielded to effect the desired thicknessdistribution along the length of the work piece. The cathode arrangementconsists of several tools (one for each compartment); each tool contains18 cathode fixtures suitably spaced apart. Suitable cathode fixturesinclude feeder rods which, if desired, can be connected to a motor toaffect their rotation at a predetermined speed. The workpieces to beplated, i.e., in the case of substrate tubes, are suitably mounted onthe cathode feeder rods. Once loaded the cathode tools containing the 18substrates each are lifted by overhead cranes and lowered into thecompartments to insert one cathode/work piece into each cell. The toolsalso contain part of the wiring and matching contacts are provided onthe multi-cell plating system and the tooling to appropriately close theelectrical circuit.

In operation, initially the tool is populated with workpieces, i.e.,tubes loaded onto the respective current feeders, in a loading/unloadingarea. The tool populated with workpieces is thereafter lifted and afteroptional metallizing and/or cleaning steps, is eventually positionedabove a plating compartment and lowered/inserted, i.e., with anautomated crane (not shown). Once loaded, the cathode tooling suitablyrests on its base using locator pins. Appropriate positioning of thecathode tool ensures that all workpieces are secured in their respectiveplating cell position. Contacts on the tools and plating system tank lipclose the contact for the rotation system and as soon as the tool restsin its appropriate place, all cathodes/workpieces can be rotated, ifdesired. Thereafter, plating is initiated by supplying electrical powerto all work pieces from the external power supplies (not shown) viasuitable wiring (not shown) to cathodes, anodes and, where applicable,thieving electrodes and the electroplating process commences. Thecurrent supplied to thieving electrode can be adjusted by appropriatelydesigning/sizing the thieving electrode to compensate for edge effectsand achieve predetermined thickness profiles. After plating has beencompleted the cathode tooling assembly is removed from the compartment,processed through appropriate washing stations, and finally returned tothe loading/unloading area.

In the case of plating three parts per string, six power supply modulesare appropriately used to power each 18 cell compartment and electricalconnections are made accordingly. FIG. 2 schematically illustrates theelectrical wiring of such an 18 cell compartment (B1) consisting of 18individual plating cells (B1-1 to B1-18), powered by six synchronizedpower supplies (PS-1 to PS-6). Each cell contains one anode (31) and onecathode (33). Each cathode 33 holds one work piece only. Three cells areconnected in series to form a 3-part string. Series connection isachieved by connecting the positive lead of the power supply PS-1 to theanode in cell B1-1, the cathode of cell B1-1 is connected to the anodeof cell B1-7, the cathode of cell B1-7 is connected to the anode of cellB1-13 and the cathode of cell B1-13 is connected to the negativeterminal of the power supply, as illustrated. The same logic is repeatedfor the remaining strings as illustrated in FIG. 2.

The power supplies PS-1 to PS-6 are connected to a central controlmodule (37) which regulates all electrical plating parameters includingthe suitable plating schedule and pulse plating regimes, if any. Thecentral control module is used to initiate and terminate platingsimultaneously in all cells by appropriately turning all power supplieson and off. The central control module also imprints the synchronizedplating schedules on all power supplies and cells, including the peakcurrent, on time, off time, reverse time and peak reverse current. Thepreset plating schedule can include a multi-step plating schedule toimpose different grain size/hardness from the substrate base to theouter surface. The plating schedule is typically chosen to finish withthe highest average current density to optimize part properties,particularly to increase the outer hardness of the deposit by suitablydecreasing the grain size. The plating schedule is typically programmedto pass the desired coulombs and, once the predetermined charge ispassed, the power supplies are turned off and the cathode tool isremoved from the multi-cell plating system and processed throughsuitable washing tanks and finally the plated work pieces are removedand new substrates inserted, upon which the entire plating process isrepeated.

Before proceeding with the examples the problems which the presentinvention is capable of solving are described hereinafter in greaterdetail. When multiple plating cells share a common electrolyte, ionicconductivity is provided by said electrolyte effectively connecting allanodes and cathode submersed in it. Persons skilled in the art ofelectrochemistry refer to this problem as shunt-currents and a number ofpart defects are caused by the presence of “shunt-currents”. Mostnotably defects include unpredicted plating thickness, weights andgeneration of plating surface defects. The degree of defects depends onthe electrolyte conductivity, the length between electrodes whichaffects the various resistivity paths and the applied voltage.Maximizing shunt current resisitivity paths in the electrolyte andminimizing the applied voltage minimizes shunt currents. Applying aseries connection between cells raises the maximum applied voltage aseach cell voltage is multiplied by the number of cells and therefore onewould ordinarily not adopt a series plating configuration. On the otherhand, if shunt currents can be totally avoided or minimized in a seriesconnection, the coulombs (=A×sec) applied to each part remains identicalassuring excellent deposit weight consistency. Specifically to pulseplating, as the peak current applied during the forward pulse andtherefore the peak voltage is even higher than in the case of DCplating, minimizing shunt currents to effect part consistency becomeseven more important.

The prior art is illustrated by Prior Art Example 1. Background isprovided by Background Examples 1-3.

The invention is illustrated in Working Examples I-VII.

Prior Art Example 1 Parallel Plating Cell of Multiple Parts in a PlatingCell System Using a Shared Electrolyte

To illustrate the prior art of plating parts simultaneously byelectrically connecting all parts in parallel and controlling the totalcurrent supplied to the plating rack known in the art as rack plating,two different parts (celluloid spheres and flat polyamide tensilecoupons) were selected.

In experiment 1 ping pong balls (40 mm diameter) made of celluloid weresuitably metallized with a Ni film (electroless nickel, MacDermid Inc.,Denver, Colo., USA) and thereafter electroplated with a nanocrystallinenickel-iron alloy (n-Ni-20Fe) layer to an average thickness of about 185μm in 4.5 hrs using the modified Watts nickel bath for Permalloy®illustrated in Table 2 using grain refiners, levelers, brighteners,specifically Nanoplate®)-B16 and Nanoplate®)-A24 (Integran TechnologiesInc., Toronto, Canada). Soluble Ni rounds (Inco Ltd., Sudbury, Ontario,Canada) and soluble Fe chips (Allied Metals Corp. of Troy, Mich.) wereemployed as anode. Plating current was supplied by a pulse power supply(Dynatronix, Amery, Wis., USA).

TABLE 2 Electrolyte Composition, Plating Conditions and Selected CoatingProperties for n-Ni—20Fe Layers. Bath Chemistry  208 g/l NiSO₄•6H₂O   36g/l NiCl₂•6H₂O   36 g/l H₃BO₃ 36.8 g/l Na₃C₆H₅O₇  9.6 g/l FeCl₂•6H₂O 4.2 ml/l Nanoplate ®-B16  1.6 g/l Nanoplate ®-A24 Plating ConditionsElectrolyte Temperature [° C.] 60 pH 2.5 Electrolyte Agitation Rate(normalized for cathode area) [ml/ 50 (min · cm²)] Rotation Speed [RPM]10 Bath Flow Direction Tangential Particulate Bath Content (insuspension) N/A Anode Shielding N/A Average Current Density (I_(avg))[mA/cm²] 100 Forward Pulse On Time [min] 280 Off Time [ms] N/A ReversePulse On Time [ms] N/A Peak Reverse Current Density [mA/cm²] N/A Totalcycle time [ms] N/A Frequency [Hz] 0 Duty Cycle [%] 100 Ni—20Fe MaterialProperties Hardness (VHN) 525 Average Grain Size [nm] 20

Table 3 illustrates the data obtained for the ball coating weights usinga single cell plating tank (40 liter bath volume) and simultaneousplating of 10 balls in parallel, i.e., all 10 parts are connected to acommon current feeder which is connected to the negative lead of thepower supply. During the plating the balls are rotating while beingsubmersed in the bath and the part rack rotates against the stationaryanode. The average plating weight in grams, the standard deviation, thestandard deviation divided by the average weight in %, the kurtosis, thehighest plating weight and lowest plating weight are displayed, as isthe weight variation expressed in percent from the average platingweight for three consecutive runs.

The data indicate that the weight consistency obtained varies from runto run with the standard deviation/average weight ratio ranging from1.6% to 5.6%. The maximum weights vary between 2.1% and 5.7% from theaverage weight and the minimum weights between 2.6% and 8.5% from theaverage weight. As these runs were performed in succession and all thecontacts were properly cleaned between runs better weight uniformity isachieved than in a typical production setting. As contacts alsodegrade/corrode with time affecting the contact resistance and therebythe local part current weight, consistencies achieved over time suffer.

TABLE 3 Position Specific Weights for Ten Ping-Pong Balls Coated Withn-Ni—Fe in Parallel in a Single-Cell Plating Tank POSITION RUN 1 RUN 2RUN 3 1 20.19 20.52 21.38 2 21.03 19.74 20.91 3 20.62 20.21 18.81 419.93 20.65 18.95 5 21.02 19.98 20.94 6 20.99 20.24 20.34 7 20.51 20.1621.32 8 21.54 20.70 21.35 9 20.86 20.55 18.50 10  20.61 19.91 19.75Average Weight [g] 20.73 20.27 20.23 Standard  0.46  0.33  1.14Deviation STDEV/Average  2.23  1.63  5.62 Weight [%] Kurtosis  0.20−1.27 −1.61 Max Weight [g] 21.54 (+3.9%) 20.70 (+2.1%) 21.38 (+5.7%)(Deviation from Average [%]) Min Weight [g] 19.93 (−3.9%) 19.74 (−2.6%)18.50 (−8.5%) (Deviation from Average [%])

In experiment 2 fine-grained Ni coatings were applied to polyamidetensile coupons (63 cm² total surface area), which had been metallizedusing electroless Ni (MacDermid Inc., Denver, Colo., USA) as above. Theelectrolyte composition and the electroplating conditions used for themodified Watt's bath for n-Ni is indicated in Table 4. Soluble Ni rounds(Inco Ltd., Sudbury, Ontario, Canada) were employed as anode. The rackwas immersed in the 100 liter bath between two anodes to affect totalencapsulation of the coupons with fine-grained nickel. Plating currentwas supplied by a pulse power supply (Dynatronix, Amery, Wis., USA) andthe plating time was 90 minutes.

TABLE 4 Electrolyte Composition, Plating Conditions and Selected CoatingProperties for n-Ni. Bath Chemistry 300 g/l NiSO₄•6H₂O  45 g/lNiCl₂•6H₂O  45 g/l H₃BO₃  5 ml/l Nanoplate ®-B16  10 ml/lNanoplate ®-A24 Plating Conditions Electrolyte Temperature [° C.] 60 pH2.5 Electrolyte Agitation Rate (normalized for cathode area) [ml/ 33(min · cm²)] Rotation Speed [RPM] N/A Bath Flow Direction UpwardsParticulate Bath Content (in suspension) N/A Anode Shielding N/A AverageCurrent Density (I_(avg)) [mA/cm²] 100 Forward Pulse On Time [ms] 20 OffTime [ms] 20 Reverse Pulse On Time [ms] N/A Peak Reverse Current Density[mA/cm²] N/A Total cycle time [ms] 40 Frequency [Hz] 25 Duty Cycle [%]50 Ni Material Properties Hardness (VHN) 425 Average Grain Size [nm] 20

Table 5 illustrates the data obtained for the polyamide coupons coatingweights using a commercial rack which was populated with 6 metallizedcoupons forming a single row in each run. The average plating weight ingrams, the standard deviation, the standard deviation divided by theaverage weight in %, the kurtosis, the highest plating weight and lowestplating weight are displayed, as is the weight variation expressed inpercent from the average plating weight for five consecutive runs.

The data indicate that the weight consistency obtained also varies fromrun to run with the standard deviation/average weight ratio ranging from˜28% to ˜43%. The maximum weights vary between ˜33% and ˜43% from theaverage weight and the minimum weights between ˜18 and ˜20% from theaverage weight illustrating the lack of accurate weight/thicknesscontrol when using a parallel plating set up.

TABLE 5 Position Specific Weights for Six Coupons Coated with n-Ni inParallel Using a Rack in a Single-Cell Plating Tank POSITION RUN 1 RUN 2RUN 3 RUN 4 RUN 5 1 10.79 11.11 10.10 10.36 10.81 2  7.05  6.96  6.73 6.58  6.72 3  6.95  6.64  6.57  6.50  6.60 4  6.62  6.39  6.60  6.53 6.53 5  6.85  6.53  7.03  6.97  6.91 6 10.36 10.53 11.22 11.55 11.32Average  8.10  8.03  8.04  8.08  8.15 Weight [g] Standard  1.92  2.18 2.07  2.26  2.27 Deviation STDEV/ 33.2 38.4 39.5 42.9 27.8 AverageWeight [%] Kurtosis −1.74 −1.70 −1.13 −1.18 −1.74 Max Weight 10.79 11.1111.22 11.55 11.32 [g]  (33.2%)  (38.4%)  (39.5%)  (42.9%)  (38.9%)(Deviation from Average [%]) Min Weight  6.62  6.39  6.57  6.50  6.53[g] (−18.3%) (−20.4%) (−18.3%) (−19.6%)7 (−19.9%) (Deviation fromAverage [%])

Background Example 1 Polarization Curves in a Single Plating Cell andMultiple Plating Cell System Using a Shared Electrolyte Obtained on Niand Carbon/Epoxy Tubes

38″ long, ˜½″ outer diameter nickel and metallized graphite/epoxy tubes(400 cm² surface area) were coated with fine-grained Ni up to a targetcoating weight of 40 g. The single plating cell comprised a tubular tank(4 ft high, ID: 1 ft, electrolyte volume: ˜90 liter) equipped with aheater, recirculation system and a single anode basket. The work piecewas mounted on a stainless steel feeder which was attached to a rotator.Similarly, in the case of the 36-multi-cell 2-compartment plating system(2500 liter) the graphite/epoxy tubes were mounted onto stainless steelcurrent feeder rods. Two cathode tools, each equipped with 18 currentfeeders each, rotational means and appropriate wiring were employed. Thesingle plating cell and the multi-cell plating system described aboveboth contained the same modified Watts nickel bath illustrated in Table4 of Prior Art Example 1. Nickel “R”-rounds (Inco Ltd., Sudbury,Ontario, Canada) were used as anode material and added to the 36 Tianode baskets, each cell contained one anode. Electrodes, electrolyteand electrode distances (4″) were identical in both tanks. In both tanksthe plating current was supplied by one or more power modules(Dynatronix, Amery, Wis., USA) pulse power supplies which weresynchronized and controlled by a central computer. The generalelectroplating conditions used are indicated in Table 6, the specificelectrical parameters used in each experiment are described below.

TABLE 6 Plating Conditions. Plating Conditions Electrolyte Temperature:60° C. pH: 2.5 Electrolyte Agitation Rate (normalized 33 ml/(min · cm²)for cathode area): Rotation Speed [RPM]: 15 Bath Flow Direction: upwardsParticulate Bath Content (in suspension): N/A Anode Shielding: Asindicated Average Current Density (I_(avg)) As indicated [mA/cm²]:Forward Pulse On Time [ms]: As indicated Off Time [ms]: As indicatedReverse Pulse On Time [ms]: As indicated Peak Reverse Current Density Asindicated [mA/cm²]: Total cycle time [ms]: As indicated Frequency [Hz]:As indicated Duty Cycle [%]: As indicated

Polarization curves were recorded for various tubes with variouselectrical contact means, with and without shielding and using directcurrent (DC) and pulse current. FIG. 3 shows the cell current/cellvoltage relationship measured in the single part plating cell for anumber of samples obtained by stepwise increasing the current from 0 Ato 100 A (250 mA/cm²) and recording the appropriate cell voltages. Curve1 shows the DC polarization curve for a Ni tube with the cell voltagecorrected for internal-resistance (IR) losses using well known currentinterruption. As expected the IR-voltage was unaffected by the selectionof the substrate (Ni or graphite-epoxy tube), the coating thickness, thecontact arrangement and the electrode distance. Curve 2 shows thecurrent/voltage response of the Ni tube using DC and through the wallelectrical contact without shielding, i.e., the coating thickness of thetube rotated at 15 RPM remains essentially the same along the tubelength and cross section. In this case of “through the wall” electricalcontacts the current is provided to the inside of the tube by astainless steel current feeder rod inserted into the ID of the tube. Theelectrical current then proceeds from the inner tube surface to theouter tube surface through the tube wall and plating is initiated at theouter tube surface where the electrochemical reduction of Ni⁺⁺ tometallic Ni occurs. Curve 4 shows the current/voltage response of thegraphite/epoxy tube rotated at 15 RPM using DC, through the wall contactand with the employ of shielding and current thieves, designed for thecoating thickness to increase of the tube within the last 13″ from 3.5mils to 7.5 mils as illustrated in more detail in Working Example III.Curve 3 shows the same arrangement as curve 4, but an additionalelectrical contact is provided to the tube's outer surface whichcontinuously reduces the Ohmic resistance of the work piece to be platedas the coating weight increases, thereby reducing the operating voltagerequired. In other words, in this arrangement current to the platingsurface is provided both (1) through the wall via the stainless steelcurrent feeder inserted in the tube and (2) directly onto the coatingsurface and the coating itself becomes another current feeder. As thecoating thickness increases, the Ohmic resistance of the coating layerdecreases and, in the case of poorly conducting substrates such asgraphite/epoxy tubes, more and more of the current to the tube isprovided through the coating layer itself. Curve 5 shows the samearrangement as curve 3 (through the wall and surface current feed), withthe exception that the current provided is not DC but a pulse currentwith a duty cycle of 50% (8 ms on followed by 8 ms off) and the averagecurrent is displayed on the x-axis. Curve 6 shows the same arrangementas curve 4 (solely through the wall current feed), with the exceptionthat the current provided is not DC but a pulse current with a dutycycle of 50% as in Curve 5. FIG. 3 illustrates the drastic effect ofpart selection, contact arrangement as well as shielding and thieving onthe total operating cell voltage and the drastic voltage increases overthe IR-free cell voltages.

Using identical parts and plating conditions, no difference was notedbetween polarization curves recorded in the single cell or themulti-cell plating system. Similarly when several parts were plated inthe multi-cell plating system as illustrated in examples to follow thepolarization curves remained essentially unchanged, other than the cellvoltages doubled when two parts were plated in series, tripled for threeparts in series and quadrupled for four parts plated in series.

Background Example 2 DC Polarization Curves of Graphite/Epoxy Tubes atDifferent Coating Weights in a Single Plating Cell and Multiple PlatingCell System

The set up used was as described in Background Example 1. In thisexperiment the part plated was a metallized graphite/epoxy tube. FIG. 4illustrates the change in polarization curves of a graphite/epoxy tubeas the Ni coating weight increases. The tube is rotated at 15 RPM at alltimes during the experiment. Curve 1 shows the DC polarization curve fora graphite/epoxy tube with the cell voltage corrected for IR losses fora “through the wall contact”. All remaining curves have been recordedusing both through the wall and surface electrical contacts and employshielding. Curve 4 shows the current/voltage response of thegraphite/epoxy tube using DC and using both through the wall and surfacecontacts with shielding/thieving, as described, before any significantdeposition of Ni occurs on the outer surface. Curve 3 shows thereduction in cell voltage after the Ni coating weight has increased to 4g and Curve 2 the voltage response after a Ni coating weight of 40 g hasbeen achieved.

Background Example 3 Pulse Current Polarization Curves of Graphite/EpoxyTubes at Different Coating Weights in a Single Plating Cell and MultiplePlating Cell System

The set up used and experiment conducted was as described in BackgroundExample 2 with the exception that DC plating was replaced by pulsecurrent deposition (50% duty cycle). FIG. 5 illustrates the change inpolarization curves of a metallized graphite/epoxy tube as the Nicoating weight increases. Curve 1 shows the average plating current fora graphite/epoxy tube with the cell voltage corrected for IR losses.Curve 4 shows the average current/voltage response of the graphite/epoxytube with 50% duty cycle (8 ms on followed by 8 ms off time) and usingboth through the wall and surface contacts with shielding/thieving, asdescribed, before any significant deposition of Ni occurs on the outersurface. Curve 3 shows the reduced cell voltage under the sameconditions after the Ni coating weight increased to 4 g and Curve 2after a Ni coating weight of 40 g has been achieved.

Working Example I Comparison of the Coating Weight Consistency Between aSingle Plating Cell and Multiple Plating Cell System Using a SharedElectrolyte

38″ long, ˜½″ outer diameter metallized graphite/epoxy tubes (400 cm²surface area) were coated with fine-grained Ni to a target coatingweight of 38.5 g using the bath chemistry outlined in Table 4 in asingle plating cell or multi-cell compartment plating system describedabove and using through the wall and surface contacts in all instances.The three specific plating schedules used and material propertiesachieved are indicated in Table 7.

TABLE 7 Electrodeposition Conditions Used and Selected CoatingProperties. Plating Schedule 1 2 3 Electrolyte Temperature [° C.] 60 pH:2.5 Electrolyte Agitation Rate (normalized 33 for cathode area) [ml/(min· cm²)] Rotation Speed [RPM] 15 Bath Flow Direction Upwards ParticulateBath Content (in suspension) N/A Anode Shielding N/A Average CurrentDensity (I_(avg)) [mA/cm²] 25 50 100 Peak Forward Current Density[mA/cm²] 61 200 400 Forward Pulse On Time [ms] 90 8 2 Off Time [ms] 0 246 Reverse Pulse On Time [ms] 10 0 0 Peak Reverse Current Density[mA/cm²] 300 N/A N/A Total cycle time [ms] 100 32 8 Frequency [Hz] 10 31125 Duty Cycle [%] 90 25 25 Ni Material Properties Hardness (VHN) 214416 470 Average Grain Size [nm] 275 85 40

This example compares the part consistency obtained in a single platingcell plating one part at a time and compares it to a multi-cellcompartment plating system for plating 36 parts at a time in twocompartments each compartment containing 18 parts in six matchingstrings, each containing 3 cells in series as illustrated in FIG. 2. Theplating schedule has been set to achieve a nominal plating weight of38.5 g (plating schedule 1 for 1 minute followed by plating schedule 2for 17 minutes, followed by plating schedule 3 for 50 minutes, totaling39 Ah per part in 68 minutes. Table 8 illustrates the data obtained.Using the single cell tank 18 tubes were plated one after the other andthe average plating weight in grams, the standard deviation, thestandard deviation divided by the average weight in %, the kurtosis, thehighest plating weight and lowest plating weight are displayed, as isthe minimum and maximum weight deviation expressed in percent from theaverage plating weight. In the case of the multi-cell plating tank onecompartment containing 18 tubes were plated simultaneously (six 3-cellstrings each controlled by its own power supply, all 6 power suppliesbeing synchronized) and the same parameters are recorded as for thesingle cell runs. The values for two consecutive separate runs aredisplayed. The data indicate that the weight consistency obtained issimilar for plating a single part at a time and for plating 18 partssimultaneously (6 strings of 3 parts in series).

TABLE 8 Coating Weight Comparison of Tubes Plated One at the Time and 18Tubes Plated Simultaneously Using the Multi-Cell Plating System. SINGLECELL MULTI- MULTI- CONTROL CELL CELL POSITION [g] RUN 1 [g] RUN 2 [g]  138.9 38.4 38.6  2 38.7 38.8 38.5  3 38.5 38.5 38.5  4 38.4 38.4 38.5  538.3 38.4 38.5  6 39.9 38.6 38.5  7 38.2 38.5 38.3  8 38.4 38.9 39.2  938.6 38.4 38.1 10 38.4 37.8 38.3 11 37.5 38.2 38.1 12 37.5 38.1 38.3 1336.7 38.5 38.2 14 37.4 39.6 40.0 15 37.2 38.4 38.1 16 39.2 38.0 38.1 1740.3 39.2 38.8 18 40.5 38.1 38.1 Average Weight [g] 38.48 38.49 38.48Standard Deviation  1.03  0.43  0.48 STDEV/Average Weight [%]  2.69 1.12  1.24 Kurtosis −0.10  1.62  5.70 Max Weight (Deviation from 40.539.6 40.0 Average) (+5.3%) (+2.9%) (+3.9%) Min Weight (Deviation from36.7 37.8 38.1 Average) (−4.6%) (−1.8) (−1.0%)

Working Example II Multiple Plating Cell System Using a SharedElectrolyte Plating 3 Cell and 4 Cell Series Strings

The multi-cell tank was wired to enable the simultaneous plating of athree and a four cell string. In the case of the three cell string, cell1, cell 7 and cell 13 were equipped with anodes and cathodes, theremaining cells contained no electrodes. In the case of the four cellstring, cell 1, cell 6, cell 11 and cell 16 were equipped with anodesand cathodes, the remaining cells contained no electrodes. 38″ long, ˜½″outer diameter metallized graphite/epoxy tubes were used as substrates.Bath composition and plating conditions were as illustrated inexperiment 1 of Background Example 1 except that the electrical platingprofile in experiment 1 consisted of two steps: (1) DC at a currentdensity of 50 mA/cm² or 20 A for 20 min, and (2) DC at a current densityof 100 mA/cm² or 40 A for 49 min. The total charge passed over the 69minute schedule amounted to 39.3 Ah. No shielding was employed.

FIG. 6 shows voltage/time profiles with curve 1 depicting the voltage ofthe 4-cell string and curve 2 denoting the voltage of the 3-cell string,respectively. Electrical contact to the work piece (graphite/epoxy tube)tube surface to be plated is achieved through the stainless steelcurrent feeder (through the wall plating) and by making contact to thesurface of the tube itself. Initially, all current is provided throughthe tube wall, but as the thickness of the metallic layer plated on thesurface builds up, more and more of the current is supplied through thecoating itself and the overall Ohmic resistance of the currentfeeder/work piece drops which results in a voltage drop with time ineach of the two constant current plating schedules as FIG. 6illustrates. Three multi-cell runs each were performed and analyzed withrespect to string to string voltage and variations. The voltage profileswere repeatable and coating weights of all parts was very similar withpart to part weight variation of less than ±2.5% regardless whetherthree or four tubes were plated simultaneously.

FIG. 7 shows voltage/time profiles for all six 3-part strings in aplating run (experiment 2) using a three step plating schedule: step 1:10 A DC for 3 minutes; step 2: 20 A DC for 16 minutes; step 3: 40 A DCfor 37 minutes for a total of 30.5 Ah in 56 minutes employing shielding.

Specifically to the shielding, ˜65% of the anode surface was coveredwith a polypropylene sheet to reduce the local current density along 25″of the tube intended to have a uniform thickness of approximately0.0035″. The shield was tapered at the transition from constant coatingthickness to increased coating thickness to gradually increase thecurrent density of the remaining 13″ of the tube to 0.0075″, asintended. As the voltage profiles were similar in all cells at all timesthe coating weights of all parts was very similar with part to partweight variation of less than ±5%.

Working Example III Comparison Between Single Plating Cell and MultiplePlating Cell System Using a Shared Electrolyte Plating 3 Cell SeriesStrings/SHIELDING

The multi-cell tank was wired to enable the simultaneous plating ofthree cell strings as illustrated in FIG. 2. Bath composition andplating conditions were as illustrated in experiment 2 of BackgroundExample 1 except that the plating schedule consisted of three steps: (1)10 A DC for 1 minute (2) 20 A DC for 17 minutes and (3) 40 A DC for 50minutes (39 Ah over 68 minutes).

Employing anode shielding and current thieves the thickness profile wasadjusted to gradually decrease the thickness of the metallic layer atone end of the tube from 0.0075″ to 0.0035″ over 13″ of the 38″ longtube, the thickness of the remaining 25″ was maintained at 0.0035″. Dueto the anode shields employed the operating voltages increased bybetween 10-25%. Specifically to the shielding, ˜65% of the anode surfacewas covered with a polypropylene sheet to reduce the local currentdensity along 25″ of the tube intended to have a uniform thickness. Theshield was tapered at the transition from constant coating thickness toincreased coating thickness to gradually increase the current density ofthe remaining 13″ of the tube to 0.0075″, as intended. The actual tapershape in the transition zone was determined by trial and error.

Current thieving was employed to smoothen the tube tip area as follows:½″ diameter, 1/16″ thick Ni-washers were mounted on a rubber stopper andthe rubber stopper/Ni-washer plugs inserted into the bottom end of thetube. The rubber stopper held the Ni-washer in place and simultaneouslysealed the tube preventing electrolyte ingress into the tube. TheNi-washer rested against the bottom end of the tube making electricalcontact to it and was therefore electroplated during a plating run.After the run the Ni-washer/rubber plug assembly was removed anddiscarded. Each washer received about 1 g of coating and ensured thatthere were no edge effects such as dendrites and the taper near the tipremained fairly liner, as intended.

Selected tube thickness profiles for four tubes plated in the singlecell tank (curve set 1) and four tubes plated in four runs of 18 tubeseach in the multi-cell system (curve set 2) as described in the tableabove are displayed in FIG. 8 which also highlights the target profile(dashed line). The Nanoplate weights of the coatings ranged from 38.0 to39.8 g. The data indicate that the thickness reproducibility is within0.001″ (measurement accuracy is ±0.0005″). Thickness measurements wereobtained cutting the tubes in ½″ intervals and using cross sectionalmetallographic techniques to measure total coating thickness andthickness uniformity. Within the measurement accuracy no changeswhatsoever in thickness uniformity on any cross-sectional cuts werenoticed which was attributed to the tube rotation during plating. As thetotal average plating weight of all tubes remained the same (38.5 g),the perceived slight increase in overall thickness of tubes plated inthe single cell tank therefore appears to be due to measurementinaccuracies. Within the limits of measurement accuracy the thicknessprofiles of all parts, regardless of the tank they were plated in, arecomparable.

Working Example IV Thickness Profile and Weight ConsistencyDetermination for the Multiple Plating Cell System Using a SharedElectrolyte/SHIELDING

The multi-cell tank and conditions described in Working Example III wereused. In a single plating run 18 parts were plated simultaneously usingone compartment and one tool populated with 18 metallized graphitefiber/epoxy tubes. Plating weight and the coating thickness 1″ from thetip of the tapered section were measured. Table 9 illustrates thatexcellent plating thickness and plating weight consistencies wereobtained.

TABLE 9 Tip Coating Thickness and Coating Weight Comparison of 18 TubesPlated Simultaneously Using the Multi-Cell Plating System. CELL TIPTHICKNESS 1″ STRING POSITION FROM THE TIP COATING NUMBER NUMBER [1,000 ×in] WEIGHT [g] 1 1 6.8 38.3 7 7.1 37.9 13 6.9 37.9 2 2 7.2 38.4 8 7.038.4 14 7.4 39.6 3 3 6.8 38.4 9 7.5 38.4 15 7.0 38.4 4 4 6.5 38.4 10 7.138.1 16 7.2 38.2 5 5 7.0 38.5 11 7.1 38.5 17 6.8 38.4 6 6 7.3 38.3 127.0 38.2 18 7.1 38.2 Run Average 7.0 38.4 Standard  0.24  0.36 DeviationSTDEV/Average  3.38  0.93 Weight [%] Kurtosis  0.65  9.09 Max Value 7.539.6 (Deviation from (+6.5%) (+3.2%) Average [%]) Min Value 6.5 37.9(Deviation from (−7.7%) (−1.2%) Average [%]) Measurement ±0.5  ±0.1Accuracy

Working Example V Weight Consistency Determination for the MultiplePlating Cell System Using a Shared Electrolyte/SHIELDING

The multi-cell tank and conditions described in Working Example III wereused. Four plating runs of 18 parts each were performed using onecompartment and one tool populated with 18 metallized graphitefiber/epoxy tubes and one run was performed plating one part at a time.Three runs were performed with the 10 A-1 minute/20 A-17 minutes/40 A-50minutes schedule for a total of 39.2 Ah within 68 minutes. In run fourthe schedule was changed to 10 A-1 minute/30 A-10 minutes/60A-34-minutes respectively for the same 39.2 Ah throughput per part butwithin a plating time of 45 minutes. The accelerated plating run (run#4) reduced the overall plating time by 23 minutes or 34% therebyincreasing the overall plating voltages. Table 10 illustrates that goodplating weight consistency was achieved in all multiple part runs withcomparable reproducibility when compared to the last run plating onepart at a time.

Table 10 also reports the maximum operating voltages in each step forthe four runs, the three “conventional” and the one “high rate” run. Thedata of the three conventional runs suggests that V_(max) per step varybetween runs. String to string voltage variations observed are typically<4V. All tube coating weights remained within 5% of the average coatingweights displaying excellent coating uniformity.

TABLE 10 Position Specific Weights and Voltages for Four Multi-CellSingle- Compartment Plating System Runs SINGLE CELL POSITION RUN 1 RUN 2RUN 3 RUN 4 CONTROL  1 38.6 38.3 38.3 38.6 38.2  2 38.6 38.4 38.5 38.738.6  3 38.8 38.4 38.4 38.9 38.4  4 38.7 38.4 34.5 38.8 38.7  5 38.738.5 38.5 38.8 38.8  6 38.6 38.3 38.3 38.7 39.2  7 38.3 37.9 37.9 38.338.6  8 38.6 38.4 38.4 38.8 38.9  9 38.7 38.4 38.6 38.8 39.1 10 38.238.1 38.1 38.7 38.7 11 38.6 38.5 38.6 39.0 38.9 12 38.3 38.2 38.2 38.538.5 13 38.2 37.9 37.9 38.2 38.5 14 39.3 39.6 40.0 39.7 38.2 15 38.738.4 37.5 38.8 38.3 16 38.2 38.2 38.2 38.6 38.7 17 38.5 38.4 38.5 38.838.2 18 38.4 38.2 38.3 38.5 38.4 Average Weight 38.6 38.4 38.2 38.7 38.6[g] Standard  0.27  0.36  1.04  0.31  0.30 Deviation STDEV/Average  0.70 0.93  2.72  0.81  0.78 Weight [%] Kurtosis  2.17  9.09 10.15  4.99−0.56 Max Weight [g] 39.3 39.6 40.0 39.7 39.2 (Deviation from (+1.8%)(+3.1%) (+4.7%) (+2.6%) (+1.5%) Average [%]) Min Weight [g] 38.2 37.937.5 38.2 38.2 (Deviation from (−1.0%) (−1.3%) (−1.8%) (−1.3%) (−1.1%)Average [%]) V_(max) Step 1 [V] 23 23 16 16 — V_(max) Step 2 [V] 20 2424 32 — V_(max) Step 3 [V] 28 27 27 39 — Plating time[min] 75 75 75 4575

Working Example VI

Weight Consistency Determination for the Multiple Plating Cell SystemUsing a Shared Electrolyte/SHIELDING

The multi-cell tank and conditions described in Working Example III wereused except that the plating schedule was revised to reduce the targetcoating weight from 38.5 g to 35.0 g. Three plating run were performedusing both compartments with two cathode tool populated with 18 graphitefiber/epoxy tubes each. Three runs, each passing 34.2 Ah, were performedusing two plating schedules. Plating schedule 1 (run #1) comprised threecurrent steps 10A-1 minute/20 A-16 minutes/40 A-43 minutes for a totalof 34.2 Ah within 60 minutes. Plating schedule 2 (runs #2 and #3)comprised five current steps 10A-1 minute/20 A-2 minutes/30 A-3minutes/40 A-4 minutes/50 A-35 minutes for a total of 34.2 Ah within 45minutes. As 34.2 Ah were used in each run, the overall plating timesdecreased by 25% from 60 minutes (run 1) to 45 min for the other tworuns. Table 11 illustrates that good plating weight consistency wasobtained.

Table 11 also reports the maximum operating voltages in each step forthe three runs, the “conventional” and the two “high rate” runsdisplaying the voltage range in each step for all 12 strings. String tostring voltage variations observed were low resulting in excellentweight and thickness profile uniformity and all tube coating weightsremained within 5% of the average coating weights displaying goodcoating uniformity.

TABLE 11 Position Specific Weights and Voltages for Three Multi-CellTwo- Compartment Plating System Runs POSITION NUMBER RUN 1 RUN 2 RUN 3 1 34.3 35.5 35.4  2 35.0 35.4 35.3  3 34.5 35.6 35.4  4 34.6 35.6 35.4 5 34.8 35.6 35.3  6 34.2 35.4 35.1  7 34.4 35.2 35.4  8 34.9 35.5 35.4 9 34.0 35.5 35.3 10 34.9 35.7 35.1 11 34.5 35.5 35.5 12 34.4 35.4 34.713 34.6 35.3 35.0 14 34.7 35.7 35.6 15 34.5 35.1 35.0 16 34.7 35.5 35.317 35.1 35.3 35.6 18 34.8 35.4 35.5 19 35.0 34.5 35.5 20 34.4 35.5 35.821 34.7 35.1 35.4 22 34.8 35.4 35.7 23 34.8 35.4 35.3 24 34.5 35.5 35.525 34.7 35.2 35.1 26 34.5 35.4 35.3 27 34.8 35.2 35.4 28 34.5 35.3 35.529 34.5 35.6 35.5 30 34.4 34.5 35.5 31 34.7 34.9 35.3 32 34.7 35.9 35.433 34.9 34.7 35.9 34 34.6 35.1 34.6 35 34.6 34.5 35.2 36 34.6 34.7 35.3Average Weight [g] 34.6 35.3 35.3 Standard Deviation  0.23  0.35  0.26STDEV/Average Weight [%]  0.68  1.00  0.74 Kurtosis  0.39  0.50  1.75Max Weight [g] (Deviation from Average 35.0 35.9 35.9 [%]) (+1.2%)(+1.7%) (+1.7%) Min Weight [g] (Deviation from Average 34.0 34.5 34.6[%]) (−1.7%) (−2.3%) (−2.0%) String V_(max) Step 1 (10A) Range [V] 18-1914-15 13-13 String V_(max) Step 2 (20 A) Range [V] 22-23 23-24 22-23String V_(max) Step 3 (30A) Range [V] N/A 30-30 29-29 String V_(max)Step 4 (40A) Range [V] 31-32 35-37 35-35 String V_(max) Step 5 (50A)Range [V] N/A 40-40 38-39 Total Plating Time [min] 60 45 45

Working Example VII

Weight Consistency Determination for the Multiple Plating Cell SystemUsing a Shared Electrolyte

The multi-cell tank and conditions described in Working Example IIexperiment 1 (three cell string) were used (see Table 12). The platingschedule consisted of two steps: 20 A for 20 minutes followed by 100mA/cm2 for 49 minutes passing a total of 39.3 Ah. No shielding wasemployed.

A number of plating runs was performed and selected parts and conditionswere manipulated to create operating voltage differences between cellsand the effect of voltage differences on coating weight uniformityassessed. The results are displayed in Table 12.

As highlighted before ideally one part at a time is plated in a singleplating tank to achieve uniform plating weights. In the multi-cellplating design all cells are ionically connected (e.g. they share oneelectrolyte hence are shorted ionically) to simplify bath management andlower the capital and operating cost. To control “shunt currents”baffles, spacers on the weirs were incorporated into the design to makethe path for shorting/current sharing as torturous as possible. Toillustrate that good plating weight uniformity can be achieved the firstrun was performed by plating three parts simultaneously in a 3-cellstring. Three Ni tubes were plated in series in run 1. To minimize shuntcurrents and maximize the electrolyte resistance between parts, cellsused were #2, #8 and #14. All the remaining cells had their respectiveanodes and cathodes submersed in their respective cells but notconnected to a power supply. Run 2 is a run plating 18 parts at a timewith the electrical configuration outlined in FIG. 2 (6 strings of 3parts in series each). Run 3 is a replication of run 1 with through thesubstrate wall plating, except for the substrates are metallizedgraphite/epoxy tubes. As the resistivity of the metallizedgraphite/epoxy tubes is much higher than the one of the corresponding Nitubes, plating voltages are significantly higher. Weight uniformity isvery poor (˜22% weight difference) indicating that some plating occurredin adjacent cells. Run 4 was similar to run 3 except that a secondaryelectrical contact was provided to the graphite/epoxy tube surface andcurrent was therefore initially supplied “through the wall” only and asthe thickness of the NiFe alloy coating increased more and more of theplating current was provided through the coated surface itself reducingthe plating voltages by ˜5V and thereby reducing the maximum voltagedifference between adjacent cells and improving plating weightconsistency. Run 5 was similar to run 3 except that the idle cells werepolarized by impressing a 6V/cell cell voltage, thereby reducing themaximum voltage difference between adjacent cells and improving platingweight consistency. Run 6 was similar to run 4 except that the idlecells were polarized by impressing a 6V/cell voltage, thereby reducingthe maximum voltage difference between adjacent cells and improvingplating weight consistency. Run 7 was similar to run 4 except that theidle cells were polarized by impressing a 8V/cell cell voltage, therebyreducing the maximum voltage difference between adjacent cells andimproving plating weight consistency.

TABLE 12 Various Multi-Cell Plating System Runs Exploring Cell VoltageDifferences Yielding Consistent and Inconsistent Plating Weights. WEIGHTMAX UNIFORMITY MAX MAX “INACTIVE” VOLTAGE OBSERVED VOLTAGE VOLTAGE CELLDIFFERENCE (MAX-MIN WEIGHT RUN RUN PER CELL PER CELL VOLTAGE OF ADJACENTDIFFERENCE NUMBER INFORMATION @ 20 A [V] @ 40 A [V] [V] CELLS [V] IN [%]AND [g]) 1 Three Metal ~4 ~7 0 4-7 2.0%/0.8 g Tubes in One 3- excellentPart String 2 18 Metal Tubes in ~4 ~7 N/A 2-5 5.9%/2.3 g 6 3-PartStrings good 3 Three ~13 ~13 0 13  21.7%/8.5 g Graphite/Epoxy poor Tubesin One 3- Part String (Through the Wall Contact Only) 4 Three ~8 ~8 0 89.7%/3.8 g Graphite/Epoxy acceptable Tubes in one 3- Part String(Through the Wall and Surface Contact) 5 As Run 3 But ~13 ~13 6 73.8%/1.5 g Inactive Cells good Polarized to 6 V 6 As Run 4 But ~11 ~8 62-5 3.8%/1.5 g Inactive Cells good Polarized to 6 V 7 As Run 4 But ~11~8 8 0-3 0.5%/0.2 g Inactive Cells excellent Polarized to 8 V

As highlighted above the high voltage differences tolerated betweenadjacent cells before the coating weight uniformity is seriouslycompromised is due to the careful system design which minimizes shuntcurrents as outlined above. Table 12 illustrates that cell to cellvoltage differences of up to 7V can be tolerated before the coatingweight consistency suffers.

In the runs where not all strings are utilized, the non-utilizedelectrodes remain at “floating electrochemical potentials”, i.e. theirrest potential while the strings being powered assume the appropriateelectrochemical potential for the applied current. While we do not wishto be bound by theory, applying an external voltage to selected stringsresults in the creation of potential differences between electrodes inadjacent cells. With most of the parameters fixed (electrolyte location,distance, ionic pathways etc.) the main variable becomes the potentialdifferences between all electrodes to each other which depends onpotential and cell voltage differences. The higher the potentialdifference e.g. between electrodes in adjacent cells the higher the riskfor appreciable “shunt currents” to develop, negatively affecting weightuniformity. In this experiment the voltage differences were created onpurpose and controlled; however, in a practical system electrodepotential differences arise for a number of reasons which can not bepredicted/controlled. Table 12 indicates that the multi-cell platingsystem used can tolerate significant potential differences betweenadjacent cells before experiencing serious weight uniformity problems.Of course the particular voltage differences which can be tolerateddepend on multi-cell system design, the electrolyte conductivity, partsresistivity, the level of shielding, applied current, etc.

Variations

The foregoing description of the invention has been presented describingcertain operable and preferred embodiments. It is not intended that theinvention should be so limited since variations and modificationsthereof will be obvious to those skilled in the art, all of which arewithin the spirit and scope of the invention.

1. An apparatus for simultaneously electrodepositing a metallic materialon at least two substrates, said apparatus comprising: an electrolytewell having at least one compartment comprising at least two ionicallyintercommunicating adjacent plating cells filled with an electrolytesolution containing ions of the metallic material to be deposited; andan electrical power source configured to supply electrical power inseries from a single source to the at least two substrates and theirrespective anodes, wherein the at least two ionically intercommunicatingadjacent plating cells are configured in a way such that at least twosubstrates are separately immersed in each of the at least two ionicallyintercommunicating adjacent plating cells so that a negative charge canbe supplied simultaneously from the electrical power source in series toprovide equal current flow to each of said at least two substrates todeposit an electrodeposited metallic material layer.
 2. An apparatus forsimultaneously electrodepositing a metallic material onto the surface ofat least four substrates in a series electrical connection, saidapparatus comprising: an electrolyte well having at least onecompartment comprising at least four ionically intercommunicatingadjacent plating cells filled with an electrolyte solution containingions of the metallic material to be deposited; and at least twoelectrical power sources, wherein the at least four ionicallyintercommunicating adjacent plating cells are configured in a way suchthat at least four substrates are separately immersed in each of the atleast four ionically intercommunicating adjacent plating cells, whereinthe at least two electrical power sources are configured in a way suchthat said a first electrical power source is configured to supplyelectrical power in series to at least two of the at least foursubstrates and their respective anodes when immersed in said ionicallyintercommunicating adjacent plating cells and a second electrical powersource of the at least two electrical power sources is configured in away such that the second electrical power source simultaneously supplieselectrical power to at least two other substrates and their respectiveanodes, and wherein the at least two electrical power sources aresynchronized to supply a negative charge to each of the at least foursubstrates to provide equal current flow to each of the at least foursubstrates for electrodepositing a metallic material layer.
 3. Theapparatus according to claim 2, wherein the at least two of the at leastfour substrates connected in series immersed in the ionicallyintercommunicating plating cells connected to the first electrical powersource are not adjacent to each other.
 4. The apparatus according toclaim 1, wherein the electrolyte solution containing ions of themetallic material to be deposited comprises a metal or an alloy of oneor more elements selected from the group consisting of Ag, Au, Cu, Co,Cr, Mo, Ni, Sn, Fe, Pd, Pb, Pt, Rh, Ru, and Zn and optionally one ormore elements selected from the group consisting of B, P, C, S and W. 5.The apparatus according to claim 1, wherein the electrolyte solutioncontaining ions of the metallic material to be deposited comprises atleast one element selected from the group consisting of: (a) one or moremetals selected from the group consisting of Ag, Au, Cu, Co, Cr, Mo, Ni,Sn, Fe, Pd, Pb, Pt, Rh, Ru, and Zn, (b) at least one element selectedfrom the group consisting of C, O and S; and (c) optionally at least oneor more elements selected from the group consisting of B, P, and W. 6.The apparatus according to claim 1, wherein the at least two substratesare selected from the group consisting of an orthopedic prosthesis, gunbarrel, mold, sporting good, cell phone and automotive component.
 7. Theapparatus according to claim 1, wherein the at least two substrates aregun barrels.
 8. The apparatus according to claim 1, wherein the at leasttwo ionically intercommunicating adjacent plating cells are configuredin a way such that the ionically intercommunicating adjacent platingcells can control electrodepositing parameters comprising averagecurrent density ranging from 5 to 10,000 mA/cm², forward pulse on timeranging from 0.1 to 10,000 ms, pulse off time ranging from 0 to 10,000ms, reverse pulse on time ranging from 0 to 500 ms, peak forward currentdensity ranging from 5 to 10,000 mA/cm², peak reverse current densityranging from to 20,000 mA/cm², frequency ranging from 0 to 1,000 Hz, aduty cycle ranging from 5 to 100%, and electrolyte temperature rangingfrom 0 to 100° C.
 9. The apparatus according to claim 1, wherein the atleast two ionically intercommunicating adjacent plating cells areconfigured in a way such that the at least two substrates are rotatedhaving a rotation speed ranging from 0 to 1,500 RPM against itsstationary anode while a negative charge is supplied to each saidsubstrate.
 10. The apparatus according to claim 1, wherein the at leasttwo ionically intercommunicating adjacent plating cells are configuredin a way such that the intercommunicating adjacent plating cells agitatesaid electrolyte solution with an electrolyte agitation rate rangingfrom 1 to 6,000 ml per min and per cm² electrode area, wherein saidelectrolyte in each of said plating cells is aqueous, has a pH rangingfrom 0 to 12, and a particulate content ranging from 0 to 70% by volume.11. The apparatus according to claim 1, further comprising a cathodetooling assembly, wherein the cathode tooling assembly is configured ina way such that the cathode tooling assembly enables the mounting andremoving of the at least two substrates to be simultaneously plated, andthe apparatus is configured in a way such that the apparatus enables thelowering of the cathode tooling assembly into the at least two ionicallyintercommunicating adjacent plating cells for simultaneouselectrodeposition.
 12. The apparatus according to claim 1, wherein saidpower sources is configured in a way such that the power sources have aplating schedule having a multi-step schedule to modulate grain size ofelectrodeposited metallic material layers.
 13. The apparatus accordingto claim 1, wherein a ratio between the total number of power suppliesand the total number of substrates is <1.
 14. The apparatus according toclaim 2, further comprising a central control module on the at least twopower sources, wherein the central control module is configured in a waysuch that the central control module imprints synchronized platingschedules for the synchronization of the at least two power sources. 15.An apparatus for simultaneously electrodepositing a metallic materialusing DC or pulse electrodeposition, said apparatus comprising: acentral electrolyte well filled with an electrolyte solution containingions of the metallic material to be deposited; at least two ionicallyintercommunicating plating cells electrically connected in series; anelectrolyte circulation loop for supplying said electrolyte solutionfrom the well to each plating cell and for returning said electrolytesolution to said central electrolyte well, each plating cell comprising(i) at least one anode, (ii) a cathode capable of receiving and holdingone of a temporary or permanent substrate to be plated optionallypositioned in relation to a thieving electrode, and (iii) means forminimizing voltage differences and shunt currents between plating cellsselected from the group consisting of divider plates, synchronized powersupplies and tortuous electrolyte pathways between cells, and at leastone power source electrically connected to at least two plating cells inseries.
 16. The apparatus of claim 15, wherein the at least one powersource is connected in series to effect uniform current flow.
 17. Theapparatus of claim 15, further comprising at least a second set of atleast two ionically intercommunicating plating cells electricallyconnected in series.
 18. The apparatus of claim 17, wherein the at leasttwo of the at least four substrates connected in series immersed in theionically intercommunicating plating cells connected to the firstelectrical power source are not adjacent to each other.